Keyfit Tools 12" Standard Size MarkerBit Driveway Marker Drill Bit Easily & Quickly drill in fiberglass & aluminum driveway stakes reflectors snow plow markers snow poles reflective markers parking lot stakes Carbide Saber Tooth Chisel Tip, Large Gap Double Flutes Designed For Fast Drilling In Dirt, Clay, Gravel, Even Frozen Ground & Solid Ice Works on all brands of STANDARD 1/4" & 5/16" Markers NOT For Flex Guard or 1/2" markers See all our products at Keyfit Tools ~Keyfit Tools Patented Products