The Trex Cortex Hidden Fastening System is the fastest, easiest way to hid deck screw heads on stairs, perimeter boards or when replacing a deck board. Easy to install, Cortex screws work with a special driving tip that automatically places the screw at the precise depth. A color-matched plug minimizes the appearance of hardware. So you get a cleaner, more attractive decking surface. • Color-matched plug made from trex decking minimizes the appearance of hardware • Installed on the boards surface • Use with square edge or grooved edge boards • Special driving tip automatically puts the cortex screw at a precise depth, then the color-matched plug is tapped in with a hammer