Made in full accordance with API 11B, the couplings are high in quality ... , Sub sucker rod coupling, Full size sucker rod coupling and Slim Hole sucker rod coupling, with the size range of 5/8", 3/4 ... you can trust in China. API 3/4” Class SM Full Size Sucker Rod Coupling 1) Material: AISI 5140 2) Standard: API ... .99mm) Length: 4" (101.6mm) Weight: 0.60kg 4)Other Size: 5/8”; 7/8”;1”; 1-1/8"5)Smoothness ...