API thread Gauges: Used for gaging API internal or external thread. Conform to: ... 5B. CSG,LCSG,LP,BCSG,TBG,UPTBG,NC.. API Thread Gauges: Used for gaging API internal and external threads.Spec 5B ... -1/2"UPTBG 1.050 to 4-1/2"All gages are produced in Drake thread grinding machine, and checked by ... will response you at the first time! API 5B Thread Gauges