Abstract: A knee pad is disclosed for cushioning a human knee. The knee pad includes a cushion section having a fluid-filled chamber. The fluid chamber is filled with a gas, a liquid, a gel, or another fluid. A knee cup is removably attached to the outer layer of the cushion section. The knee cup is interchangeable, so that a knee cup of an appropriate material may be attached for the particular activity the wearer is engaged in. The knee pad is held on the knee by at least one fastening strap. Each fastening strap is removably attached to the cushion section, so that it may easily be replaced when worn out. The invention also includes a knee pad set having two or more interchangeable knee cups for various construction jobs and/or sports.