Non-corrosive stainless steel construction. A head is coated to match coloured boards. Ideal for all composite boards and pressure-treated timbers where a secure, neat, flush fix is needed. A small head sits beneath the surface of the board, sealing the composite and eliminating rot. Triple thread provides exceptional grip. First thread secures the screw into the joist or substrate, second thread draws swarf beneath the surface of the joist allowing the top board to sit flush and third thread secures board to a joist.