The Moore and Wright Reversible Base Depth Gauges have accurately ground top and bottom faces to allow the base to be reversed perfect for use in confined spaces. There is a full range rule adjustment and the readings can be fixed by means of a locknut. Rules are graduated on both sides. The Moore & Wright 43M Reversible Base Depth Gauge has the following specification: Size of Base: 18/56mm.Width: 5.5mm.Thickness: 1.0mm.Length of Blade: 195mm. Metric Scale Graduations : Front Face: 0.5mm and 1.0mm, Rear Face: 1.0mm.