Cable rail installation isn't rocket science, but there are a lot of fittings and specialized tools involved. Feeney - a major manufacturer and supplier of architectural cable and fittings - has put together a series of installation videos that will help familiarize you with how its Quick-Connect cable rail fittings work, and demonstrate how to install them in 4x4 rail posts that are fitted with standard composite sleeves. In this system, there are two basic types of fittings for each cable assembly. Fixed ends are non-adjustable end termination fittings that have no tensioning capabilities. Tension adjustment fittings are used to tighten the cable lines, which is done by spinning the tubular bodies on the swivel turnbuckles. Each fixed end fitting must be paired with a tension adjustment fitting. And while these videos clearly explain cable layout and installation, they don't address post installation, which is critical to the overall performance of a cable rail system. Rail posts need to be strong enough to resist the considerable tension loads typical of a cable rail system.