These anodized aluminum 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 (1-1/4in) tall, to help maintain accuracy throughout the cut. The machined reference face has three embedded 12.7mm (1/2in) dia. rare-earth magnets and is covered with a strip of low-friction UHMW tape. The magnets help maintain tool contact with the guide while the tape allows tools to glide along the reference face.
The bottom of the guide has two high-friction strips to resist slipping on a surface.
The guides are available in 200mm (8in) and 355mm (14in) lengths.