... ,N80-Q 3.Placement:female 4.Std Ref: API 5ct & 5b Detailed description Coupling manufacturer of Tubing and Casing coupling according to API ... products by customer's request3.Size:tubing coupling from 1.9"to 4-12",casing coupling from 4-1/2" to 13 ... -3/8"4.Type:NU,EU(tubing coupling),STC,LC,BTC(casing coupling)5.Surface treatment: whole phosphating, or inside phosphating ...