Rock-On Star Flat Head Cement Board Screws make installation of tile easy, fast, and secure. Their patented serrated head design allows for countersinking at any angle, while the T-25 bit provides Stikfit, making installation a one-handed job. With a Climacoat corrosion-resistant finish, you won't have to worry about rust from bleeding into grout. Install with a standard impact or drill/driver for perfect tile surfaces in any high-moisture area!