A cap turns an open box into a dry, lockable, out-of-sight space, and it is one of the accessories people keep for the life of the truck. That is exactly why it is worth taking a minute over the decisions below before ordering one.
Start with how you use the truck
Be honest about the two or three things the box does most weeks. A contractor loading tools every morning wants different doors and racking than a family that mostly keeps hockey bags and groceries dry. A hunter or angler cares about a lockable rear door and window options. Someone who tows a fifth-wheel needs to know whether the cap will clear the trailer. The cap that suits one of those people is often wrong for another.
Height
A cab-high cap follows the roofline of the cab. It looks like it belongs on the truck, keeps fuel economy and parking-garage clearance close to stock, and suits most everyday use. A mid-rise or high-rise cap adds interior height for taller cargo, shelving or standing room at the tailgate, at the cost of a taller profile and more wind resistance. Commercial users usually go tall; most personal trucks stay cab-high.
Material
Fibreglass caps are the familiar painted, colour-matched shells. They are quiet, look finished, take paint well and are the usual choice for personal trucks. Aluminum caps are lighter, cheaper, and easier to fit with doors, racks and toolboxes, which makes them the working choice for trades. They are not painted to match, so they look like equipment rather than bodywork, which is fine on a work truck and less so on a family one.
Doors and access
The rear door is a given. The decision is what else opens. Side-access doors (sometimes called walk-in or tool-access doors) let you reach the front of the box without climbing in, and they are the single most useful upgrade for anyone loading tools daily. Sliding side windows help with airflow and visibility. If you plan to sleep in the box or run a camper setup, ask about screened windows and interior lighting.
Glass, locks and finish
Tinted glass keeps the contents out of sight and the box cooler in summer. Frameless rear doors look cleaner; framed doors take more abuse. Most caps use a single key for all doors; a remote lock that works from the truck's fob is available on many models. On fibreglass, a factory colour-match is done to the paint code on the door jamb, so have that handy when you order.
Fit
Caps are built to the box, not the truck. The same model of truck can have two or three box lengths and the box shape changes between generations, so the cap is ordered against the year, make, model, box length and bed style. If you have a spray-in liner, bed rails or a tonneau track already on the truck, mention it, because it affects the clamps and seals. A cap that is ordered right fits without drilling and seals without leaks; a cap that is guessed at does neither.
Racks and extras
If you carry ladders, kayaks or lumber, decide on the roof rack at the same time as the cap, because the mounting points are built into the shell. Interior carpet, cargo lights, a dome light on the rear door, and a headliner are all easier to add at the factory than afterwards.
Tell us the truck and what you do with it, and we will narrow the options to two or three caps that make sense, with a price for each fitted.