Empire 396 12” Polycast Rafter Marking Square A speed square is also known as the rafter angle square, rafter square, and triangle square. This is a multi-purpose triangular carpenter tool that is used for marking. Carpenters use it to make the basic measurement and mark lines on the dimensional lumber, and they see it as a guide for 45 to 90 degrees cut. The rafter square was made for scribing lines quickly. It has a lipped straight edge that provides 90° and 45° angles. Holding the lip of the rafter square against a board, you can mark out perfect perpendicular and 45° lines. You can do this as quickly as it takes to slide the rafter square around. Durable POLYCAST® material Provides 90° and 45° angles Molded conversion tables Easy to see graduations repeated on both sides Made in the USA