Rock slider

Also called sliders, rock rails, rocker protection

A rock slider is a frame-mounted bar running along the side of a vehicle that can take the vehicle's full weight on an obstacle, protecting the rocker panel and giving you something to pivot on deliberately.

What is a rock slider?

A steel tube or box section running between the wheels along the bottom of the body, bolted or welded to the frame rails. Its job is to be the thing that hits when the middle of the vehicle comes down on a rock, so that the rocker panel and the floor pan do not.

The second job is the one that gives it its name. A slider lets you set the vehicle down on an obstacle on purpose, slide along it, and pivot around it, which is a technique rather than an accident on tight technical trails.

Sliders are not side steps

This is the distinction that matters and the one the aftermarket blurs. A running board or nerf bar mounts to the body or to brackets on the pinch weld. It is there to help people climb in. Put the weight of a truck on it and it folds, and it takes a section of the body with it.

A slider mounts to the frame, because the frame is the only part of a vehicle that can take that load. If a product mounts to the body, it is a step, whatever the listing calls it.

What they cost

Weight, typically eighty to a hundred and forty pounds for a pair in steel, all of which comes out of payload. Width, which matters on a tight trail between trees. And on some designs, a step that is now further out and lower than the factory one, which is a daily-life cost people notice more than they expected.