Knee pads made by Invader Gear for the knee pad pocket of your pants.
The protectors are two-piece, the foam padding part closest to the leg is a piece of foam, to which a hard plastic outer protector is attached with Velcro. This hard plastic piece can be replaced separately if desired, and the entire protector does not need to be removed from the pants. The outer protector is located outside the knee pad pocket. Fits most manufacturers' pants with an opening for the outer plastic protector. One size.