Retrax IX Retractable Tonneau Cover for 2015-2020 Ford F-150 (5'7" Bed)

Here's the short version. Follow Retrax's install sheet (below) for your truck's exact steps, part letters and torque settings.

1. Assemble on the bed. Set the canister assembly on the bulkhead and bed rails, centered across the truck. Slide the rails into the canister tabs, line up the holes and drive the 10-32 x 0.750 Torx screws in with the T-25 bit until flush with the rail; Retrax notes they are self-tapping and take force.
2. Build the clamps and stops. Thread a nylon set screw into the side of each clamp and a 5/16-18 bolt into its bottom (1.625" long, or 2.25" on GM trucks). Put a 5/16-18 x 0.50 bolt and nylon lock nut, left loose, on each rail end cap and latch stop.
3. Set the latch stops. Slide a latch stop into each rail and set the front one 1/16" from the rail fastener, then slide in the other stops and clamp nuts in the order the sheet shows. With the front seal lying flat on the bulkhead (trimmed so it doesn't pass the bed rail caps), fit the rail end caps and set both rails 1/8" from the tailgate with the 1/8" spacer. Put the rear latch stop flush against the end cap. Optional middle stops go in equal numbers on both sides, evenly placed; tighten stop fasteners to no more than 5 ft-lb.
4. Fit the clamps. Slide one clamp nut as far toward the cab as it goes and one toward the tailgate, thread in the clamp bolts and set the clamps close to the latch stops, clear of bed sheet metal and plastic rail caps. Tighten until they no longer slide, to no more than 5 ft-lb. The Tundra short bed (2007-2021), the Ram 1500 (2009-2018), 1500 Classic and 2500/3500 bed and the 2019+ Ranger use different clamps or rails, and 2019+ GM trucks add adhesive rubber shims; follow your truck's page in the sheet.
5. Square the rails. Line the cover rails up straight with the spiral rail section and turn each clamp's nylon set screw in until it touches the bed rail. Measure across on top of the front cover and above each clamp; they must match within 1/16". Adjust with the set screws, then re-tighten all the clamps.
6. Drain tubes. Push a drain tube into each side of the canister and turn it clockwise until it clicks twice. Route them out through a hole drilled in the factory bed plug or another suitable hole, checking for lines before you drill. When the cover isn't in use, keep it latched in the latch stops so it can't roll.