The Skimmer Plug offers a simple and proven method to winterize above ground and in ground pool skimmers without draining any water. A rigid outer plate made of ABS plastic and air tight seal prevent freezing during those harsh winter months as a durable and secure layer of protection resists chemicals, temperature and even UV rays. The skimmer plug securely fits into the skimmer opening using an exclusive Rovaseal thermo insulated layer to plug off and grip the faceplate. No tools are required, simply press the skimmer plug flush all the way against your existing skimmer faceplate to close off the skimmer. DB-Series fits above ground Doughboy pool skimmers and includes vacuum port plug. Inside Dimensions: 5-5/8 X 7-13/16 inches.