... 9 3/4" API Drill Collar Specifications 1.standard:API7-1 2.OD:79.4mm-279.4mm 3.factory directly delivery 9 3/4 ... drill collars are manufactured strictly from API Spec7-1 standard. HEXIN own the leading heat treatment ... to Standards of API 5DP, API7 &7-1, NS-1. RUSSIA RTN, RUSSIA GOST-R, ISO 9001 ... ,ISO 14001, OHSAS 18001, Arnco Hardbanding Certificates and so on. 9 3/4 ...