When installing 8′ Trex Select railings, this Aluminum Rail Stiffener can be used to allow for the rail to be stronger if required. If installing 8′ rail section and using the Aluminum Rail Stiffener, predrilling will be required through the stiffener. Trex Select is luxurious-yet-affordable railing that offers an easy installation process that’s perfect for the DIYer. The Trex Select 8′ Aluminum T-Rail Stiffener provided extra support for 8′ T-Rail top rails. Built with heavy duty aluminum, the T-Rail Stiffener slide right in the top rail. Only works with Trex Select T-Rail top rails.