Rock-On 23316 Serrated Head Star Drive Cement Board Screws, 9" x 1"-5/8", 575-PkThe Rock On 1 1 4 in. 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. 575 pack Size: 9" x 1" 5 8" Serrated head design for flush seating even at an angle Patented sharp point offers immediate pick up and eliminates the need to pre