FYOU PMEC is the leading supplier of gauges for both plug & ring thread gages in china, FYOU PMEC will meet your requirements and custom build your thread gages to meet your exact specifications. Our gage engineering team is ready to design and work with you on all your thread gaging needs; FYOU PMEC provide a complete line of API ( American Petroleum Institute) plug and ring gages for( both working & masters) : BCSG CSG NC IF TBG( NU) UP TBG REG FH 4 1/ 2 BCSG 4 1/ 2 CSG NC23 2 3/ 8 IF 2 3/ 8 TBG ( NU) 2 3/ 8 UP TBG( EUE) 2 3/ 8 REG 2 7/ 8 FH 53BCSG 53CSG NC26 2 3/ 7 IF 2 7/ 8 TBG ( NU) 2 7/ 8 UP TBG( EUE) 2 7/ 8 REG 3 1/ 2 FH 5 1/ 2 BCSG 5 1/ 2 CSG NC31 3 1/ 2 IF 3 1/ 2 TBG ( NU) 3 1/ 2 UP TBG( EUE) 3 1/ 2 REG 4" FH 6 5/ 8 BCSG 6 5/ 8 CSG NC35 4 " IF 4“ TBG ( NU) 4 UP TBG( EUE) 4 1/ 2 REG 4 1/ 2 FH 7“ BCSG 7“ CSG NC38 4 1/ 2 IF 4 1/ 2 TBG ( NU) 4 1/ 2 UP TBG( EUE) 5 1/ 2 REG 5 1/ 2 FH 7 5/ 8 BCSG 7 5/ 8 CSG NC40 5 1/ 2 IF 6 5/ 8 REG 6 5/ 8 FH 8 5/ 8 BCSG 8 5/ 8 CSG NC44 7 5/ 8 REG 9 5/ 8 BCSG 9 5/ 8 CSG NC46 8 5/ 8 REG 10 3/ 4 BCSG 10 3/ 4 CSG NC50 11 3/ 4 BCSG 11 3/ 4 CSG NC56 13 3/ 8 BCSG 13 3/ 8 CSG NC61 16“ BCSG 16“ CSG NC70 18 5/ 8 BCSG 18 5/ 8 CSG NC77 20 BCSG 20 CSG