Bestway Flowclear sunshade keeps the heat/water in and the debris out The sunscreen creates a greenhouse effect which keeps the water/heat in the pool while keeping leaves and other debris out of the water. The chlorine level also stays longer with this cover. Economical and environmentally friendly. Specifications - PE material - The solar cover uses solar energy to heat the pool water and prevents the heat from dissipating. - Minimizes debris in the pool Contents: One pool sun shield