This Faithfull specialist level is designed to ensure fence posts are upright prior to fixing. Other uses include plumbing pipes, levelling of RSJs and other applications where a vertical and horizontal is needed. The durable plastic angle plate has 2 acrylic horizontal vials and 1 vertical vial that are accurate to 1.75mm per 1m = 0.1 . There are 2 fixing methods 1. Elastic strap for non-magnetic surfaces. 2. Magnetic base for use on RSJs and steel fence posts. Size 140 x 90 x 90 mm.