The SUNPACK SUNPAD 20.75in x 48in heat mat is perfect for any gardener looking to start seeds or root cuttings indoors. From beginners to professionals, this mat is reliable and easy to use. It warms the root zone 10-20 degrees Fahrenheit above the ambient air temperature, cultivating the perfect environment for cuttings and seedlings. This mat is waterproof and gives gardeners peace of mind that they are creating the perfect environment for their plants. This size is about four times as big as the smaller size we carry. This size will perfectly fit four standard 1020-size trays.