1/2"x6" Pilot bit works with the whole rig to start the coring process. Must use with the Drill Bit Warehouse Dry Core Bit System. Specially manufactured in Germany using titanium-microcarbide. This bit starts the drilling process on any stone, granite, tile, concrete, and asphalt materials faster then anything we have ever seen. You will only need one of these per rig assembly. Can interchange between Core-Bits.