All spa covers are UL Approved and manufactured using only top quality materials, providing you a durable and lasting spa cover. Manufactured using marine grade vinyl and energy efficient polystyrene inserts. Inserts are heat sealed with a poly vapor moisture barrier to protect against water absorption. UV inhibitors in both the vinyl and thread prevent premature aging of your spa cover, which all add up to a superior product against water absorption. Our covers are available in any size, with over 1000 patterns available or custom made to fit any spa.