Creates a tight fit quickly and easily and features evenly-spaced pressure points that only apply pressure on the right fingers. Slots on the outside of the cauls are made to hold pennies in place to firmly support band clamps at varying heights. Makes clamping box joint fast, accurate, and secure. Compatible with Rockler 25mm (1) x 4.5m (15) Band Clamp (sold separately). Creates a tight fit quickly and easily and features evenly-spaced pressure points that only apply pressure on the right fingers. Slots on the outside of the cauls are made to hold pennies in place to firmly support band clamps at varying heights. Makes clamping box joint fast, accurate, and secure. Compatible with Rockler 25mm (1) x 4.5m (15) Band Clamp (sold separately).