Haige provides full range of API 5CT Tubing Couplings, API5CT Casing Couplings and Special Clearance Couplings for oil and gas operation. Special Clearance Couplings Specifications: Diameters: 2 3/8" through 20" Grades: J55, K55, N80-1, N80Q, L80, P110, Q125 Connections: EUE, BTC