Vermont Black Guard Pin Set .5010 - .6250Vermont Class ZZ Black Guard Pin Set Black Guard Pin Gages include a black oxide treatment that helps prevent corrosion and also shows gage wear, saving money and time. The Black Guard black oxide treatment typically penetrates 0. 00004" 0. 00006" deep, which will visually reveal wear patterns allowing the inspector to calibrate or replace the gage pins more effectively. Black Guard treatment will also help prevent rust and corrosion which will extend