This is a very nice, clean twist drill gauge marked "CT-701 DRILL GAUGE FISHER AIRCRAFT", and also has precision holes and number marking by each hole for twist drills number with the smaller number drill #55 to the largest #8, there is also fractions from 1/16"-1/2", and letter drill sizes from B to W. Most likely made as a drill gauge for specific application since not all the letters, numbers, and fractions sizes are on this gauge. The gauge plate measures 2.38" x 6.25". This one is in nice clean shape, no rust, and no sign of wear, very nice shape overall!