Spa 5" Light Lens Kit with Silicon to Seal when installing Clear Plastic Housing Fits 3 3/4" Hole in Shell Better Chemical Resistance Comes with Lens, Gasket, Nut and Light Holder This part is a Clear 5" Hot Tub Light Lense Kit with the gasket, Nut, Light Holder and 2.8oz of Silicon sealer . The face size is 5" and the hole size is 3 3/4" This fits most tubs that have a large light lens but some tubs have a Lens close to 5" that has a smaller hole than this requires but you can use this lens by making the hole larger with a rat tail file. The reason they are replaced is due to extreme Chemical damage that causes them to crack and leak. Please verify your hole size before ordering. Compare the pictures and be sure. For a Video about these light lens parts go to YOUTUBE and look for "Spa Hot Tub 5" Light Lens Info Hot Tub Professor How To Series"