Quick Overview The Cover Cap is made from tough, durable woven polyethylene designed to protect your spa and spa cover during the harsh winter months. The Cover Cap is available in black and silver, and for any hot tub shape or size. We offer custom sizes for your cover cap and will contact you for your hot tub's dimensions to ensure a perfect fit. For instance, if your spa measures 86" x 86", we will build your cover cap for 88" x 88", a difference of 1" on each side. Please add 2" to each measurement (Width and Length) to ensure a proper fit. Add room for your cover lifter if you are using one.