It consists of a clear storage container with some drainage holes drilled in the bottom. There is a string of clearance Christmas rope lights wrapped around the bottom and caulked in place. The cord comes out the side through a drilled hole. After all the caulk was dry 2 inches of sand was put in the bottom to cover the lights completely, the sand helps hold the heat. The original instructions said to keep the lid on the storage tote but we found that the temperature got very hot (100 degrees or more) with it on. The total came to around $10 for everything, much cheaper than the $40 seed heating mats you see in gardening centers.