Rock On 23315#9 x 1-5/8 in. Zinc-Plated Wafer-Head Phillips Screws (600 Pack) Used for for attaching Cement Board to Wood and Light-Gauge Steel, Multi Ideal for attaching durock and wonderboard to light gauge steel Use these screws on a variety of projects including work with bathtubs, Showers, Countertops and flooring applications Climacoat coating provides protection against rust and corrosion Deep high low threads allow quick entry and provide maximum holding power Zinc-plated steel construction