On mine there is an upper block above the table, and a lower one under the table. The blocks are just rectangular with a blade thickness slot 25 thou in my case, cut to a depth so that the teeth project but the rest of the blade is supported. You fit blocks to suit your blade, 1/4 3/8 1/2 etc . Their mounting is adjustable front to back and side to side, but not in anyway for pinch.