I purchased this cover for my Behlen stock tank, which is popular for, and I use as, an ice recovery / ice bath through the Wim Hof Method. (I had been covering it with a tarp secured around the perimeter by two large bungee cords.) I ordered the cover with the zipper. The order was thorough, requesting a variety of measurements. Both the cover and zipper are well-made; the cover fits like a loose glove. As I'm in a warm west coast climate, I will be adding insulation around the tank, and the cover will fit snugly and contribute to extending a cooler bath temperature. Highly recommended as a protection for the variety of stock tanks for which Alco provides custom covers.