3/4" Hole Saw. The Laird Hole Saw features a replaceable self-centering pilot bit (HS34DB) that prevents dangerous "walking" of the saw and a replaceable hardened saw blade (HS34RB). It also features a 1/8" depth limit that will prevent damage to the underlying headliner, yet it is deep enough to cut through thicker aluminum surfaces encountered on utility vehicles and ambulances. Ut is designed for a 3/8 drill chuck and is nickel-plated to guard the tool against corrosion.