2PK Seedling Heat Mat with ETL Listed,Warm Hydroponic Heating Pad for Seed Starting,Indoor Gardening,Brewing and Greenhouses,Durable Waterproof Black Plant Heat Mat Works with 20″x10″ Gardening Tray. Durable & Waterproof Design: This heat mat is made with soft, flexible, long-lasting material and an SPT-2 5.9ft waterproof power cord.