Spax 4.5 x 60mm Wirox C4 Torx Decking screw (Tub 250)

C4 Accredited: 15 Years without Corrosion Serrations on lower thread for quick and safe fastening. Non-threaded shank allows the two materials to be pulled tightly together Upper thread locks the deckboard securely. T20 T-star drive (bit included)