Rafter's Square.

Manufactured from hardened and tempered ground steel. Graduated to 2mm on one side and 1/8" and 1/16" increments on the other. In hands of a skilled carpenter the simple rafters square becomes an indispensable calculating device of immense capacity. Enabling the carpenter to easily determine the length of any common, hip, valley or jack rafter for any pitch of roof. To make the proper cuts, top and bottom as well as slide or cheek cuts for any rafter.