Dynasty Spas 50175 17' Gray Pro Swim Spa Cover with 6" to 4" Taper - This Dynasty Spas Cover has various uses for your spa. It prevents heat loss from your spa which allows you to get your spa up and running quickly. Harsh weather conditions stand no chance with this cover, as it is able to keep rain, snow and other debris out. It also serves as a good solution for preventing unsupervised access, especially by young children.