Betterley Tru-Cut Blade Insert System. Fits Delta Left Tilt 10 inch Unisaw and Delta Hybrid Saw Patented design is precision engineered to maximize the performance of your table saw and blades Machined flat aluminum, mirrors table surface completely to blade, giving unparalleled support Leveling system insures accuracy, spring-loaded side plungers position insert, prevents vibration Significantly increases safety and decreases kickback, pre-machined for factory splitter/guard Insert measures 3-3/4" x 13-3/8" - Will not fit new Unisaw with a riving knife.