Pool Mate 1-3804--BLK-04 Cover Water Bags, 4-Pack, 4 ft. Black Product Details Size: 4-Pack Color: Black Material: Vinyl Brand: Pool Mate Product Dimensions: 4"L x 1"W Style: Single Chamber - 4 ft. Model Name: Heavy-Duty 16 Gauge 4-Foot Single Chamber Special Feature: Heavy Duty Theme: Plain Shape: Rectangular Closure Type: Drawstring Pattern: Solid Installation Type: [MANUAL] Product Care Instructions: [Some Care Required, Instructions Not Specified] UPC: 06 Item Weight: 3.59 pounds Manufacturer: 1-3804--BLK-04 Country of Origin: China Item model number: 1-3804--BLK-04 Is Discontinued By Manufacturer: No 4-Pack Black 4 ft. Single Chamber 16 Gauge Pool Cover Water Bags Heavy-Duty 16 Gauge Vinyl Construction - 30% Heavier Than Industry-Standard Single Chamber Design For Easy Filling Prevents Winter Pool Cover From Falling Into Pool Fill Halfway With Water to Allow For Ice Expansion - If you have trouble closing the valve please use a hair dryer to loosen before closing. Pool Mate 4 foot single chamber water tubes are constructed of heavy-duty 16 Gauge puncture resistant vinyl. All of our water tubes have a conveniently placed, leak-proof valve that is easy to fill with a garden hose. Water tubes keep your pool cover in place all winter long. Water tubes should be filled half-way to prevent popping caused by expansion if the water freezes.