Precision cast iron square with level vial and hardened scribe toolStainless steel hardened bladesGraduated blade 1/32” one side, metric 0.01 mm on other sideExtremely accurate for layoutsCan measure depths or shoulders faster than a depth micrometer without changing stems, can reach from 0.0 to 9.3 inches in seconds.Can be used with or without side accessory blade.Accessory blade is useful to reach across gaps or extend out from edges, also can be used to hook behind a corner.Remember to reset zero when using accessory scaleFloating zeroFitted in plastic box