The single valve tube that performs as a double! Match your Armorkote winter cover with these deluxe water tubes, available in blue, black, and tan. The intermittent center seal allows water to weave through placing water on both sides through a single valve fill opening. Water is evenly disbursed, cuts down on filling time. The "heat activating" black color slows the process of water freezing protecting the water tube, ensuring a more secure cover installation reducing the risk of tube failure. Made in North America!