he Cortex Hidden Fastening System is the fastest, easiest way to hide fasteners in composite, capstock, and PVC decking boards. Cortex offers a strong connection between the deck board and joist. It hides fasteners across the entire deck, first and last board, perimeter, and stairs. Just set the screws in place and the setting tool makes sure you hit the perfect depth every time. After the screw is installed just place the provided plugs in place and hammer down. You now have a securely fastened deck without any of the unsightly fasteners!