API Class SM coupling 1ú¬Type: SM FS and SH coupling 2ú¬Coupling diameter: 5/8 ",3/4",7/8",1",1-1/8" 3)Weight: 0.41-1.29 KG/Pcs 4ú¬Material: AISI 5I40 5ú¬Spray Materialú¦Ni60A Alloy Coating 6ú¬SM Thicknessú¦0.01-0.02in 7) Basic Hardness: HRC 16-23 8ú¬Surface Hardness: HRC 55-62 9ú¬Hole rate: ú+2% 10ú¬Min. Hardness of the layer: 595HV0.2 11) Operating Temperature: -1000~400íµ 12) Life: > 180 days 13ú¬Standard: API Spec 11B 14)Package: wooden case 15)Payment Terms: T/T . Our New Products 1) SM Coupling with great bevel edge 2) Two-way Cambered Protection Coupling If you have any interest in our sucker rod couplings, please do not hesitate to let we know, and weí»ll supply you with our high quality products and best services.