Made of a proprietary elastomer with unique flow and set characteristics to fill irregular gaps. Size B – 3″ x 3″. Slot Size – 78″. Tab makes shim placement easier and safer, while eliminating the need to place hands under the machinery during installation or removal of shim. Blue Sof’ Shoe® elastomer shims are 0.020″ thick, compress to 0.0175″, and absorb up to 0.010″ of angularity.