Made of reinforced, UV treated 10 mil polyethylene. Fits around tree trunk. Simply fill to desired level and let water drip. Depending on configuration, on average one bag holds 20 gallons of water and drips for 5 to 9 hours. Use more than one bag by zipping together. One bag fits trees 1˝ to 3˝ in diameter. Two bags fit trees 4˝ to 8˝ in diameter. Heavy duty nylon zippers, polypro straps, and strong, durable heat sealed edges.