Omg Fmctx-az100bs Cortex Concealed Deck Fastening System Azex Brownstone The deck boards are fastened in the same way as with a traditional deck A through-fastened deck offers the highest level of board-to-joist connection and deck racking strength The Cortex system is less expensive than virtually any other hidden fastening system and it is so easy to install! Deck pros will save money and save time installing it.