These lat bars will attach to any cable machine in the gym such as a lat machine or cable crossover machine. A lat bar is a special bar that you can grip anywhere along its length for narrow or wide grip pulldowns while sitting on a bench.
Rubber grips on lat bars give you a few advantages: First, they give you that extra bit of grip strength due to friction, They keep your hands warm in the Winter months when gripping a bare steel bar would be like gripping an icicle. Finally, they are easy on your hands and won't cause callouses like the knurled surface of uncovered steel.
We have some extra-thick "fat" lat pulldown bars that are meant for intermediate and advanced lifters to work on their grip strength. It's a lot harder to pull down a 2" bar than it is a 1" bar that your fingers wrap more fully around.