Manufactured from hardened stainless steel with dual reading in Imperial to 0.001 in. & in Metric to 0.02 mm. The universal four-way measurement facility enables reading in External Internal Depth & Step modes. The sliding thumb lock feature easily allows quick & precise measurements to be taken. The satin finished scales & beam ensure fast easy & accurate readings. A strong plastic storage case provides a secure home for this precision instrument Size 150 mm. (6 in.).