In pursuit of the perfect deck, all Trex® decking lines come with a hidden installation option. When using grooved-edge boards, Trex hidden deck fastening system installs between the deck boards, fastening them to the joists with no visible deck screw heads on the walking surface. The Start Clip & Connector Clip These are black, stainless steel fasteners designed exclusively for Trex and used to install the perimeter deck boards.