It's quick work to measure the depth of a space using this analogue depth gauge from RS PRO. Finding the depth simply involves sliding the ruler down, tightening the spring-loaded finger clamp and taking the reading.
The ruler is marked on both sides for ease of use and the base and top surface have been ground for use as datum faces. The bevelled surface of the datum face makes it easy to read the rule, which is marked with both imperial and metric scales. The ruler is made from fully hardened steel for durability and can be used to measure depths up to 150 mm.
The gauge meets the American National Standards Institute (ANSI) ESD S20.20:2014 and British Standard (BS) EN 61340-5-1:2007 electrostatic control standards, so it's guaranteed not to damage equipment via electrostatic discharge. It's ideal for general use in workshops and machine shops.

• Analogue display type
• Both imperial and metric
• Stainless-steel material
• Maximum measurement of 150 mm
• Resolution of 1 mm, 1/32 in
• Weight of 470 g