These anodized aluminium guides help keep a saw square to a workpiece. They are particularly useful when crosscutting tenon shoulders or defining the edges of a dado, since the guide helps a backsaw track straight and true. Held against a workpiece with a hand or secured with clamps (not included), it provides a registration surface, about 32mm tall, to help maintain accuracy throughout the cut. The machined reference face has three embedded 12.7mm dia. rare earth magnets and is covered with a low-friction UHMW pad. It also has a T-slot to accept a pair of 50mm capacity clamps (available separately).