Insize 2237-20, INTERNAL THREAD CREST DIAMETER MEASURING INSTRUMENT, 4 1/2″-20″/114.3-508mm, 6928640384684

Dial indicator graduation .0005″
Accuracy .002″
Measure the crest diameter of internal thread with nominal diameter larger than 2 3/8″(60.325mm) and less than 20″ (508mm)
Optional accessory: height standard and zero standard block