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 and Wright 43 Reversible Base Depth Gauge has the following specification: Size of Base: 18/56mm, 0.71/2.21in.Width: 5.5mm/0.22in.Thickness: 1.0mm/0.04in.Length of Blade: 195mm/7.68in. Metric/Imperial Scale Graduations : Front Face: 1/32nd, Rear Face: 1.0mm.