1.standard:API7-1 2.OD:79.4mm-279.4mm 3.factory directly delivery 4.Alloy steel,carbon steel,stainless steel etc. ... brand drill collars are manufactured strictly from API Spec7-1 standard. The product quality and stability, the customers satisfaction is 100 ... , Heavy Weight Drill Pipe, Kelly,Pup Joint and so on. (Factory)API 7-1 Spiral Drill Collar--Drilling tool