Based on a pair of aluminium bodied heads with knurled brass locking nuts, this trammel set will help you accurately set out or cut circles or arcs. The heads will fit onto any steel ruler with a thickness of 1mm or less and a width between 22mm and 30mm. The length of your ruler is the only limit to the maximum diameter you can draw. Each trammel head features a small cut-out. This cut-out allows you to read the position of the head on the rule’s scale. For example, aligning one cut-out with the 10mm mark on your rule and the other with the 110mm mark, will give you an exact radius of 100mm. This takes a lot of the guesswork out of setting-up. Supplied with two hardened steel trammel points, ten pre-sharpened pencil leads and a scalpel blade.