These silicone end caps are used for re-sealing waterproof LED strip lights that have been cut to a custom length. Easy use for LED RGB Flexible Strip. White Silicone design helps give it a hidden "invisible" look while not obstructing light from the strip. End cap is 12mm wide and will fit RGB LED Strip lights and so on. They are commonly used to re-seal and re-waterproof LED strips after cutting or resizing them.