Northern gauge manufactures API Internal Flush (I.F.) working, reference and regional master gages per API specification 7-2 for sizes from 2 to 6-5/8 inches in diameter. All working gages are manufactured and certified using a certified API reference master gage as required by the standard.
|INTERNAL FLUSH (I.F.)|
|4 (NC46) (4-1/2 XH)||4||2||V-0.065|
|4-1/2 (NC50) (5 XH)||4||2||V-0.065|