Keep water and heat in and debris, leaves, and trash out of your pool with this Bestway® Solar Pool Cover. Above ground swimming solar pool covers create a greenhouse effect in your pool. Solar covers also prevent water evaporation caused by dry winds, or free-chlorine loss caused by UV rays. These covers are designed to keep water and heat in, but debris out. Extend your swimming season with a Bestway® Solar Pool Cover. Fits 12'/3.66m Fast Set™ and Steel Pro™ Pools.