I have seen many sliders that will use standard skateboard knee pads and will then run a seam of gorilla tape around the top and bottom of the pads to be certain that the pads will not slide down while in motion. Some sliders even recommend using the catchers knee guards that baseball players wear. As for gloves most of the time theses are custom made by the sliders. I would like to throw out a word caution though... Many of the people that I have talked to say that while they love to slide, it has often caused serious permanent damage to their knees. I know and am good friends with two people who have been long time sliders and are skilled at what they do who have had multiple permanent injuries due to sliding.