I'm fairly sure those are nerf steps made by N-fab. They and smittybilt are the only company I know of that makes nerf bars with steps like that. Last time I checked neither made any for 4th gen 4runners.
nerf bars and sliders are complete different animals, the one in your picture could get you hang up on a big rock between the 2 hoops. hint the word "slider" which can carry the load of the truck slide over rocks.