These Silicone Cleaning Plugs are used to keep 420 solutions inside the piece to properly clean. It’s easy and efficient and will make the experience of cleaning your piece with ease.set includes 3 different size plugs. 1- Large: fits 12mm-26mm wide openings. 1-Medium: fits 8mm -18mm wide openings. 1-Small: fits 6mm-14mm wide openings.