Sun2Solar Compensator Winter Guard For Above Ground Swimming Pool Skimmer (9-Inch) Measures: 1-1/2-in. wide x 9-in. long Designed for above ground pool skimmers The quickest, safest way to close your pool. You never need to drop your water level again. Fits almost all standard skimmers. The Compensator universal expansion plug closes off the skimmers drain hole while the adjustable contraction bottle absorbs ice expansion.