1)strict API standard 2)First-class reputation from registered customers 3) ... 614.9822.31E,X,G, S0.3378.56EU IEUNC46,NC504-1/2114.32018.6927.84E,X,G, S.04310.92EU ... .624.0335.79X,G, S0.512.7EU IEUNC50.5,1/2FH5-1/2139.721.919.8129.51E,X,G, S0.3619 ... 54IEU5 1/2FHAll drill pipes above mentioned meet the standard of API Spec 5D;Any qustion,please contact us!Skype:angela257000 API-5DP standard oil drill ...