1.Name:sucker rod coupling 2.Size:full size 3.Class:T 4.Hardness:HR56-62HRA 1) Coupling Materials: Seamless Alloy Steel 40Cr (AISI 5140)2) Class: T& SM , Sub Coupling3) Main specification: 5/8", 3/4", 7/8", 1", 1-1/8"4) Package: wooden case SM Full Size sucker rod coupling of Oil equipment