Rock-On Cement Board Screws are designed for attaching Durock, Wonderboard or equivalent glass-mesh cement backerboard to wood or light gauge steel studs. Rock-On's patented serrated head design countersinks for flush seating at any angle, providing a smooth surface for tile. The Star drive recess with T-25 bit provides Stikfit for one-handed installation. Rock-On screws feature a Climacoat corrosion resistant finish that prevents rust from.. See full description for further details