I find myself hauling things that are higher than the sides of my truck quite often so I got a shell. Very rarely do I haul anything taller than the truck. But just in case I got it clamped on. 30 minutes and it's off.

Examples? Lawnmower, trees, couch, computer racks, etc.. But that's me. I thought long and hard about just getting a cap but I also wanted to be able to sleep in the truck bed when I went fishing.

I also rigged up a 12v power adapter near the tailgate, off of the shell's light. It's an "alway on" source. I would recommend this for anyone as you have an easy charging station.