Every pool has a skimmer and during the winter season when water freezes it expands, the expansion can break your skimmer. Just place the Skim-Insure into your skimmer when you close your pool for the winter to absorb any expansion caused by freezing water. The freezing water will actually compress the Skim-Insure instead of expanding outward and cracking your skimmer. The skim-Insure absorbs the expansion and the water crushes the guard instead of destroying the skimmer. It's that simple; and this product is much like the Gizzmo or Skimmer-Guards that are out on the market, but for half the price. So why spend more money when you can get the same results with the new Skim-Insure! We now offer a special BlowOut version of the skimmer plug! This plug allows you to blow out the skimmer line while the plug is installed. Now there is no need to drain your pool with this BlowOut model.