TECHNICAL INFO

  • Table For Comparison Of General Steel Grades

    No. GB ГОСТ ASTM BS JIS NF DIN
    1 08F 08КП 1006 040A04 S09CK C10
    2 8 8 1008 045M10 S9CK C10
    3 10F 1010 040A10 XC10
    4 10 10 10,101,012 045M10 S10C XC10 C10,CK10
    5 15 15 1015 095M15 S15C XC12 C15,CK15
    6 20 20 1020 050A20 S20C XC18 C22,CK22
    7 25 25 1025 S25C CK25
    8 30 30 1030 060A30 S30C XC32
    9 35 35 1035 060A35 S35C XC38TS C35,CK35
    10 40 40 1040 080A40 S40C XC38H1
    11 45 45 1045 080M46 S45C XC45 C45,CK45
    12 50 50 1050 060A52 S50C XC48TS CK53
    13 55 55 1055 070M55 S55C XC55
    14 60 60 1060 080A62 S58C XC55 C60,CK60
    15 15Mn 15Г 10,161,115 080A17 SB46 XC12 14Mn4
    16 20Mn 20Г 10,211,022 080A20 XC18
    17 30Mn 30Г 10,301,033 080A32 S30C XC32
    18 40Mn 40Г 10,361,040 080A40 S40C 40M5 40Mn4
    19 45Mn 45Г 10,431,045 080A47 S45C
    20 50Mn 50Г 10,501,052 030A52 S53C XC48
    080M50
    21 20Mn2 20Г2 13,201,321 150M19 SMn420 20Mn5
    22 30Mn2 30Г2 1330 150M28 SMn433H 32M5 30Mn5
    23 35Mn2 35Г2 1335 150M36 SMn438(H) 35M5 36Mn5
    24 40Mn2 40Г2 1340 SMn443 40M5
    25 45Mn2 45Г2 1345 SMn443 46Mn7
    26 50Mn2 50Г2 ~55M5
    27 20MnV 20MnV6
    28 35SiMn 35CГ En46 37MnSi5
    29 42SiMn 35CГ En46 46MnSi4
    30 40B TS14B35
    31 45B 50B46H
    32 40MnB 50B40
    33 45MnB 50B44
    34 15Cr 15X 5115 523M15 SCr415(H) 12C3 15Cr3
    35 20Cr 20X 5120 527A19 SCr420H 18C3 20Cr4
    36 30Cr 30X 5130 530A30 SCr430 28Cr4
    37 35Cr 35X 5132 530A36 SCr430(H) 32C4 34Cr4
    38 40Cr 40X 5140 520M40 SCr440 42C4 41Cr4
    39 45Cr 45X 51,455,147 534A99 SCr445 45C4
    40 38CrSi 38XC
    41 12CrMo 12XM 620CR.B 12CD4 13CrMo44
    42 15CrMo 15XM A-387Cr . B 1653 STC42 12CD4 16CrMo44
    STT42
    STB42
    No. GB ГОСТ ASTM BS JIS NF DIN
    43 20CrMo 20XM 41,194,118 CDS12 SCT42 18CD4 20CrMo44
    CDS110 STT42
    STB42
    44 25CrMo 4125 En20A 25CD4 25CrMo4
    45 30CrMo 30XM 4130 1717COS110 SCM420 30CD4
    46 42CrMo 4140 708A42 42CD4 42CrMo4
    708M40
    47 35CrMo 35XM 4135 708A37 SCM3 35CD4 34CrMo4
    48 12CrMoV 12XMΦ
    49 12Cr1MoV 12X1MΦ 13CrMoV42
    50 25Cr2Mo1VA 25X2M1ΦA
    51 20CrV 20XΦ 6120 22CrV4
    52 40CrV 40XΦA 6140 42CrV6
    53 50CrVA 50XΦA 6150 735A30 SUP10 50CV4 50CrV4
    54 15CrMn 15XГ,18XГ
    55 20CrMn 20XГCA 5152 527A60 SUP9
    56 30CrMnSiA 30XГCA
    57 40CrNi 40XH 3140H 640M40 SNC236 40NiCr6
    58 20CrNi3A 20XH3A 3316 20NC11 20NiCr14
    59 30CrNi3A 30XH3A 3325 653M31 SNC631H 28NiCr10
    3330 SNC631
    60 20MnMoB 80B20
    61 38CrMoAlA 38XMIOA 905M39 SACM645 40CAD6.12 41CrAlMo07
    62 40CrNiMoA 40XHMA 4340 871M40 SNCM439 40NiCrMo22
    63 60 60 1060 080A62 S58C XC55 C60
    64 85 85 C1085 080A86 SUP3
    1084
    65 65Mn 65Г 1566
    66 55Si2Mn 55C2Г 9255 250A53 SUP6 55S6 55Si7
    67 60Si2MnA 60C2ГA 9260 250A61 SUP7 61S7 65Si7
    9260H
    68 50CrVA 50XΦA 6150 735A50 SUP10 50CV4 50CrV4
    69 GCr9 ШX9 E51100 SUJ1 100C5 105Cr4
    51100
    70 GCr9SiMn SUJ3
    71 GCr15 ШX15 E52100 534A99 SUJ2 100C6 100Cr6
    52100
    72 GCr15SiMn ШX15CГ 100CrMn6
    73 Y12 A12 C1109 SUM12
    74 Y15 B1113 220M07 SUM22 10S20
    75 Y20 A20 C1120 SUM32 20F2 22S20
    76 Y30 A30 C1130 SUM42 35S20
    77 Y40Mn A40Г C1144 225M36 45MF2 40S20
    78 ZGMn13 116Г13з└ SCMnH11 Z120M12 X120Mn12
    79 T7 y7 W1-7 SK7,SK6 C70W1
    80 T8 y8 SK6,SK5
    81 T8A y8A W1-0.8C 1104Y175 C80W1
    No. GB ГОСТ ASTM BS JIS NF DIN
    82 T8Mn y8Г SK5
    83 T10 y10 W1-1.0C D1 SK3
    84 T12 y12 W1-1.2C D1 SK2 Y2 120 C125W
    85 T12A y12A W1-1.2C XC 120 C125W2
    86 T13 y13 SK1 Y2 140 C135W
    87 8MnSi C75W3
    88 9SiCr 9XC BH21 90CrSi5
    89 Cr2 X L3 100Cr6
    90 Cr06 13X W5 SKS8 140Cr3
    91 9Cr2 9X L 100Cr6
    92 W B1 F1 BF1 SK21 120W4
    93 Cr12 X12 D3 BD3 SKD1 Z200C12 X210Cr12
    94 Cr12MoV X12M D2 BD2 SKD11 Z200C12 X165CrMoV46
    95 9Mn2V 9Г2Φ 2 80M80 90MnV8
    96 9CrWMn 9XBГ 1 SKS3 80M8
    97 CrWMn XBГ 7 SKS31 105WC13 105WCr6
    98 3Cr2W8V 3X2B8Φ H21 BH21 SKD5 X30WC9V X30WCrV93
    99 5CrMnMo 5XГM SKT5 40CrMnMo7
    100 5CrNiMo 5XHM L6 SKT4 55NCDV7 55NiCrMoV6
    101 4Cr5MoSiV 4X5MΦC H11 BH11 SKD61 Z38CDV5 X38CrMoV51
    102 4CrW2Si 4XB2C SKS41 40WCDS35-12 35WCrV7
    103 5CrW2Si 5XB2C S1 BSi 45WCrV7
    104 W18Cr4V P18 T1 BT1 SKH2 Z80WCV S18-0-1
    2018/4/1
    105 W6Mo5Cr4V2 P6M3 N2 BM2 SKH9 Z85WDCV S6-5-2
    06-05-04-02
    106 W18Cr4VCo5 P18K5Φ2 T4 BT4 SKH3 Z80WKCV S18-1-2-5
    18-05-04-01
    107 W2Mo9Cr4VCo8 M42 BM42 Z110DKCWV S2-10-1-8

  • Table For Comparison Of Stainless Steel Grades

    No. GB ГОСТ DIN NF JIS AISI/ ASTM UNS SAE BS ISO SS14
    1 1Cr17Mn6Ni5N 12X17T9AH4 - - SUS201 201 S20100 30201 - A-2 -
    2 1Cr18Mn8Ni5N 12X17T9AH4 X8CrMnNi189 Z15CNM19.08 SUS202 202 S20200 30202 284S16 A-3 2357
    3 1Cr18Mn10Ni5Mo3N - - - - - - - - - -
    4 2Cr13Mn9Ni4 20X13H4T9 - - - - - - - - -
    5 1Cr17Ni7 09X17H7Ю X12CrNi17.7 Z12CN17.07 SUS301 301 S30100 30301 301S21 14 -
    6 1Cr17Ni8 - X12CrNi17.7 - SUS301J1 - - - - - -
    7 1Cr18Ni9 12X18H9 X12CrNi18.8 Z10CN18.09 SUS302 302 S30200 30302 302S25 12 2331
    8 Y1Cr18Ni9 - X12CrNiS18.8 Z10CNF18.09 SUS303 303 S30300 30303 303S21 17 2346
    9 Y1Cr18Ni9Se 12X18H10E - - SUS303Se 303Se S30323 30303Se 303S41 17 -
    10 1Cr18Ni9Si3 - X12CrNiSi18.8 - SUS302B 302B S30215 30302B - - -
    11 0Cr18Ni9 08X18H10 X5CrNi18.9 Z6CN18.09 SUS304 304 S30400 30304 304S15 11 2332
    2333
    12 00Cr18Ni10 03X18H11 X2CrNi18.9 Z2CN18.09 SUS304L 304L S30403 30304L 304S12 10 -
    13 0Cr19Ni9N - - - SUS404N1 304N S30451 - - - -
    14 0Cr19Ni10NbN - X5CrNiNb18.9 - SUS304N2 XM21 S30452 - - - -
    15 00Cr18Ni10N - X2CrNiN18.10 Z2CN18.10 SUS304LN 304LN S30453 - 304S62 - 2371
    (Az)
    16 1Cr18Ni12 12X18H12T X5CrNi19.11 Z8CN18.12 SUS305 305 S30500 30305 305S19 13 -
    17 0Cr18Ni12 8X18H12T、06X18H11 X5CrNi19.11 Z8CN18.12 - - - - - - -
    18 0Cr23Ni13 - X7CrNi23.14 - SUS309S 309S S30908 30309S - - -
    19 0Cr25Ni20 - - - SUS310S 310S S31008 30310S - - 2361
    20 0Cr17Ni12Mo2 08X17H13M2T X5CrNiMo18.10 Z6CND17.12 SUS316 316 S31600 30316 316S16 20,20a 2347
    21 1Cr17Ni12Mo2 10X17H13M2T - - - - - - - - -
    22 0Cr18Ni12Mo2Ti 08X17H13M2T X10CrNiMoTi18.10 Z6CNDT17.12 - - - - 320S31 - 2343
    320S17 -2350
    No. GB ГОСТ DIN NF JIS AISI/ ASTM UNS SAE BS ISO SS14
    23 1Cr18Ni12Mo2Ti 10X17H13M2T X10CrNiMoTi18.10 Z8CNDT17.12 - - - - - - 2350
    24 00Cr17Ni14Mo2 03X17H14M2 X2CrNiMo18.10 Z2CND17.12 SUS316L 316L S31603 30316L 316S12 19,19a 2353
    25 0Cr17Ni12Mo2N - - - SUS316N 316N S31651 - - - -
    26 00Cr17Ni13Mo2N - X2CrNiMoN18.12 Z2CND17.12 SUS316LN 316LN S31653 - 316S61 - 2375
    (AZ)
    27 0Cr18Ni12Mo2Cu2 - - - SUS316J1 - - - - - -
    28 00Cr18Ni14Mo2Cu2 - - - SUS316J11 - - - - - -
    29 0Cr18Ni12Mo3Ti 08X17H15M3T - Z6CNDT17.13 - - - - - - -
    30 1Cr18Ni12Mo3Ti 10X17H13M3T X10CrNiMoTi18.12 Z8CNDT17.13B - - - - - - -
    31 0Cr19Ni13Mo3 08X17H15M3T X5CrNiMo17.13 - SUS317 317 S31700 30317 317S16 25 -
    32 00Cr19Ni13Mo3 03X16H15M3 X2CrNiMo18.16 Z2CND19.15 SUS317L 317L S31703 - 317S12 24 2367
    33 0Cr18Ni16Mo5 - - - SUS317J1 - - - - - -
    34 1Cr18Ni9Ti 12X18H9T X12CrNiTi18.9 Z10CNT18.10 SUS321 321 S32100 30321 321S20 - 2337
    35 0Cr18Ni10Ti 08X18H10T X10CrNiTi18.9 Z6CNT18.11 SUS321 321 S32100 30321 321S12 15 -
    36 1Cr18Ni11Ti 12X18H10T - - - - - - 321S20 - -
    37 0Cr18Ni11Nb 08X18H12B X10CrNiNb18.9 Z6CNNb18.10 SUS347 347 S34700 30347 347S17 16 2338
    38 1Cr18Ni11Nb 12X18H12B - - - - - - - - -
    39 0Cr18Ni9Cu3 - - Z6CNU18.10 SUSXM7 XM7 S30430 - - D32 -
    40 0Cr18Ni13Si4 - - - SUSXM15J1 XM15 S38100 - - - -
    41 0Cr26Ni5Mo2 08X21H6M2T X8CrNiMo275 - SUS329J1 329 S32900 - - - 2324
    42 1Cr18Ni11Si4AlTi 15X18H12C4TЮ - - - - - - - - -
    43 1Cr21Ni5Ti 12X21H5T - - - - - - - - -
    44 00Cr18Ni5Mo3Si2 - - - - - - - - - -
    45 00Cr24Ni6Mo3N - - - - - - - - - -
    46 0Cr13A1 1X12CЮ X7CrAl13 Z6CA13 SUS405 405 S40500 51405 405S17 2 2302
    47 00Cr12 - - - SUS410L - - - - - -
    48 1Cr15 - - - SUS429 429 S42900 51429 - - -
    49 00Cr17 - - - SUS430LX - - - - - -
    50 1Cr17 12X7 X8Cr17 Z8C17 SUS430 430 S43000 51430 430S15 8 2320
    51 Y1Cr17 - X12CrMoS17 Z10CF17 SUS430F 430F S43020 51430F - 8a 2383
    No. GB ГОСТ DIN NF JIS AISI/ ASTM UNS SAE BS ISO SS14
    52 1Cr17Mo - X6CrMo17 Z8CD17.01 SUS434 434 S43400 51434 434S17 9c 2325
    53 00Cr17Mo - - - SUS436L - - - - - -
    54 00Cr18Mo2 - - - SUS444 18Cr2Mo - - - - -
    55 1Cr25Ti 15X25T X8Cr28 - - 446 S44600 51446 - - 2322
    56 00Cr27Mo - - Z01CD26.1 SUSXM27 XM27 S44625 - - - -
    57 00Cr30Mo2 - - - SUS447J1 - S44700 - - - -
    58 1Cr12 - - - SUS403 403 S40300 51403 403S17 - 2301
    59 0Cr13 08X13 X7Cr13、X7Cr14 Z6C13 SUS410S 410S S41008 - 430S17 1 -
    60 1Cr13 12X13 X10Cr13 Z12C13 SUS410 410 S41000 51410 410S21 3 2302
    61 1Cr13Mo - X15CrMo13 - SUS410J1 - - - - - -
    62 Y1Cr13 - X12CrS13 Z12CF13 SUS416 416 S41600 51416 416S21 7 2380
    63 2Cr13 20X13 X20Cr13 Z20C13 SUS420J1 420 S42000 51420 420S37 4 2303
    64 3Cr13 30X13 X30Cr13 Z30C13、Z30C14 SUS420J2 - - - 420S45 5 2304
    65 3Cr13Mo - - - - - - - - - -
    66 Y3Cr13 - - Z30CF13 SUS420F 420F S42020 51420F - - -
    67 4Cr13 40X13 X46Cr13、X40Cr13 Z40C13、Z40C14 SUS420J2 - - - - - -
    68 3Cr16 - - - SUS429J1 - - - - - -
    69 1Cr17Ni2 14X17H2 X22CrNi17 Z15CN16-02 SUS431 431 S43100 51431 431S29 9 2321
    70 7Cr17 - X40CrMo15 Z45CSD10 SUS440A 440A S44002 51440A - - -
    71 8Cr17 - - - SUS440B 440B S44003 51440B - - -
    72 9Cr18 95X18 - - SUS440C - - - - - -
    73 11Cr17 - X105CrMo17 Z100CD17 SUS440C 440C S44004 51440C - A-16 -
    74 Y11Cr17 - - - SUS440F 440F S44020 51440F - - -
    75 9Cr18Mo - - - - - - - - - -
    76 9Cr18MoV - X90CrMoV18 - SUS440B 440B S44003 51440B - - -
    77 0Cr17Ni4Cu4Nb - X5CrNiCuNb17.4 Z6CNU17.04 SUS630 630 S17400 17-4PH - 1 -
    78 0Cr17Ni7A1 09X17H7Ю1 X7CrNiAl17.7 Z8CNA17.7 SUS631 631 S17700 17-7PH - 2 -
    79 0Cr15Ni7Mo2A1 - X7CrNiMoA15.7 Z8CND15.7 - 632 S15700 - - 3 -

  • Table For Comparison Of Copper Alloys

    SORT GB DIN EN ISO UNS JIS
    BRASS H96 CuZn5 2.0220 CuZn5 CW500L CuZn5 C21000 C2100
    H90 CuZn10 2.0230 CuZn10 CW501L CuZn10 C22000 C2200
    H90 CuZn10 2.0230 CuZn10 CW501L CuZn10 C22000 C2200
    H85 CuZn15 2.0240 CuZn15 CW502L CuZn15 C23000 C2300
    H80 CuZn20 2.0250 CuZn20 CW503L CuZn20 C24000 C2400
    H70 CuZn30 2.0265 CuZn30 CW505L CuZn30 C26000 C2600
    H68 CuZn33 2.0280 CuZn33 CW506L CuZn35 C26800 C2680
    H65 CuZn36 2.0335 CuZn36 CW507L CuZn35 C27000 C2700
    H63 CuZn37 2.0321 CuZn37 CW508L CuZn37 C27200 C2720
    HPb-63-3 CuZn36Pb1.5 2.0331 CuZn35Pb1 CW600N CuZn35Pb1 C34000 C3501
    HPb-63-3 CuZn36Pb1.5 2.0331 CuZn35Pb2 CW601N CuZn34Pb2 C34200 -
    H62 CuZn40 2.0360 CuZn40 CW509N CuZn40 C28000 C3712
    H60 CuZn38Pb1.5 2.0371 CuZn36Pb2 CW608N CuZn36Pb2 C35000 -
    HPb63-3 CuZn36Pb3 2.0375 CuZn36Pb3 CW603N CuZn36Pb3 C36000 C3601
    HPb59-1 CuZn39Pb2 2.0380 CuZn39Pb2 CW612N CuZn38Pb2 C37700 C3771
    HPb58-2.5 CuZn39Pb3 2.0401 CuZn39Pb3 CW614N CuZn39Pb3 C38500 C3603
    - CuZn40Pb2 2.0402 CuZn40Pb2 CW617N CuZn40Pb2 C38000 C3771
    - CuZn28Sn1 2.0470 CuZn28Sn1As CW706R CuZn28Sn1 C68800 C4430
    - CuZn31Si1 2.0490 CuZn31Si1 CW708R CuZn31Si1 C44300 -
    - CuZn20AI2 2.0460 CuZn20AI2 CW702R CuZn20AI2 C68700 C6870
    COPPER TU2 OF-Cu 2.0040 Cu-OFE CW009A Cu-OF C10100 C1011
    T2 E-Cu58 2.0065 Cu-ETP CW004A Cu-ETP C11000 C1100
    TP2 SF-Cu 2.0090 Cu-DHP CW024A Cu-DHP C12200 C1220
    TP1 SW-Cu 2.0076 Cu-DLP CW023A Cu-DLP C12000 C1201
    BRONZE QSn4-0.3 CuSn4 2.1016 CuSn4 CW450K CuSn4 C51100 C5111
    CuSn5 2.1018 CuSn5 CW451K CuSn5 C51000 C5102
    QSn6.5-0.1 CuSn6 2.1020 CuSn6 CW452K CuSn6 C51900 C5191
    QSn8-0.3 CuSn8 2.1030 CuSn8 CW453K CuSn8 C52100 C5210
    NICKEL SILVER BZn18-18 CuNi18Zn20 2.0740 CuNi18Zn20 CW409J CuNi18Zn20 C76400 C7521
    BZn12-24 CuNi12Zn24 2.0730 CuNi12Zn24 CW403J CuNi12Zn24 C75700 C7541
    BZn12-26 CuNi18Zn27 2.0742 CuNi18Zn27 CW410J CuNi18Zn27 C77000 C7701

  • Thread Identification Chart (Metric Screw Threads)

    Nominal Diameter / D(mm) Pitch in mm / P
    1st Series 2nd Series 3rd Series Coarse Pitch Fine Pitch
    3 2 1.5 1.25 1 0.75 0.5 0.35 0.25 0.2
    1 0.25 0.2
    1.1 0.25 0.2
    1.2 0.25 0.2
    1.4 0.3 0.2
    1.6 0.35 0.2
    1.8 0.35 0.2
    2 0.4 0.25
    2.2 0.45 0.25
    2.5 0.45 0.35
    3 0.5 0.35
    3.5 0.6 0.35
    4 0.7 0.5
    4.5 0.75 0.5
    5 0.8 0.5
    5.5 0.5
    6 1 0.75
    7 1 0.75
    8 1.25 1 0.75
    9 1.25 1 0.75
    10 1.5 1.25 1 0.75
    11 1.5 1 0.75
    12 1.75 1.5 1.25 1
    14 2 1.5 1.25 1
    15 1.5 1
    16 2 1.5 1
    17 1.5 1
    18 2.5 2 1.5 1
    20 2.5 2 1.5 1
    22 2.5 2 1.5 1
    24 3 2 1.5 1
    25 2 1.5 1
    26 1.5
    27 3 2 1.5 1
    28 2 1.5 1
    30 3.5 -3 2 1.5 1
    32 2 1.5
    33 3.5 -3 2 1.5
    35 1.5
    36 4 3 2 1.5
    38 1.5
    39 4 3 2 1.5
    1st Series 2nd Series 3rd Series Coarse Pitch Fine Pitch
    8 6 4 3 2 1.5
    40 3 2 1.5
    42 4.5 4 3 2 1.5
    45 4.5 4 3 2 1.5
    48 5 4 3 2 1.5
    50 3 2 1.5
    52 5 4 3 2 1.5
    55 4 3 2 1.5
    56 5.5 4 3 2 1.5
    58 4 3 2 1.5
    60 5.5 4 3 2 1.5
    62 4 3 2 1.5
    64 6 4 3 2 1.5
    65 4 3 2 1.5
    68 6 4 3 2 1.5
    70 6 4 3 2 1.5
    72 6 4 3 2 1.5
    75 4 3 2 1.5
    76 6 4 3 2 1.5
    78 2
    80 6 4 3 2 1.5
    82 2
    85 6 4 3 2
    90 6 4 3 2
    95 6 4 3 2
    100 6 4 3 2
    105 6 4 3 2
    110 6 4 3 2
    115 6 4 3 2
    120 6 4 3 2
    125 8 6 4 3 2
    130 8 6 4 3 2
    135 6 4 3 2
    140 8 6 4 3 2
    145 6 4 3 2
    150 8 6 4 3 2
    155 6 4 3
    160 8 6 4 3
    165 6 4 3
    170 8 6 4 3
    175 6 4 3
    180 8 6 4 3
    185 6 4 3
    190 8 6 4 3
    195 6 4 3
    200 8 6 4 3
    205 6 4 3
    210 8 6 4 3
    215 6 4 3
    220 8 6 4 3
    225 6 4 3
    230 8 6 4 3
    235 6 4 3
    240 8 6 4 3
    245 6 4 3
    250 8 6 4 3
    255 6 4
    260 8 6 4
    265 6 4
    270 8 6 4
    275 6 4
    280 8 6 4
    285 6 4
    290 8 6 4
    295 6 4
    300 8 6 4
    Remark :
    1、A screw thread in conformity with this International Standard is designated by the letter M followed by the values of the nominal diameter and of the pitch expressed in millimeters separated by the sign x. Example : M 10 x 1 (Fine pitch 1mm)
    2、The absence of the indication of pitch means that the coarse pitch is specified. Example : M 10 (Coarse pitch 1.5)
    3、The words "coarse" and "fine" are given in order to conform to usage. No concept of quality however, is associated with these words. "Coarse" pitches are the largest metric pitches used. For the diameter selected, choose one of the pitches shown on the corresponding line.
    4、 1st Series ---- 1st Choice.
    2nd Series ---- 2nd Choice.
    3rd Series ---- 3rd Choice.
    5、Try to avoid using the size in parentheses.