With no installation or tools required, the Skimmer Plug™ securely fits into the skimmer opening using insulated expanding layer to plug and grip the faceplate, creating a 100% air/water-tight seal. Ice is no match for the Skimmer Plugs rigid outer plate, providing a durable and secure layer of protection through the winter. This is a standard Model Square Mouth skimmer plug for above ground pools. Mouth measurements. 5 5/8" high x 5 7/8" wide. Hayward 1090, 1091LX, Aquadoor 1090, Kokido K001WBX, JED 45-402, Poolmaster 32190, Pro Line 60496, and others. Please be sure to check the skimmer mouth opening for proper model purchase. This model fits skimmer mouths 11.5"W x 5-3/16"H