Helps provide even moisture for successful seed starting. Both over and under-watering can cause stress to small, delicate seedlings. This special felt-like fabric wicks moisture from the water reservoir in the seed tray and delivers it to plants as they need it. A protective cover prevents roots from growing into the mat. Each 21" wide x 8' long mat can be cut to accommodate eight 11"x21" flats or cut to any other desired size.