The Delta 78-431 Biesemeyer T-Square, Anti-Kickback, Snap-In Spreader increase the table saw safety. Designed for use with over arm guards for through-cutting operations, the snap-in design allows quick removal for dado cutting. Reduces dangerous kickbacks, the spreader snaps on instantly and removes easily from 36-820L, 36-821L and other Left-Tilt Unisaws.