The Rivet Gauge is for sizing pop rivets from #3 to #8 diameters and blind threaded inserts from 6-32 to 3/8". This tool also has a handy 5" ruler. The Rivet Gauge is made of sturdy plastic and is water, alcohol, oil & grease resistant. It is very informative, but compact and is a user friendly reference tool. Custom color match for orders 2500 pieces or more. 3.5" W x 5 1/4" L x 1/8" Thick