Professional high precision tool! depth measuring base allows the conversion of a standard caliper to a depth gauge. It attaches to the bottom end of calipers to aid depth measurement. Its locking nut secures the base to the caliper. Made of stainless steel, high precision ground and hardened easily attached with screw knob. No modification to caliper. Allow using a standard caliper as a depth gauge accommodates blades up to 5/8 inch or 16mm wide total span 2.93 inch.