Save 30% in watering and nutrient costs! CubeCaps are a USA and internationally patented water and fertilizer conservation tool, designed for commercial greenhouse and hobby growers. They are used as a vapor barrier cover for any and all types of growing mediums. Besides being used on square blocks, they can also be used on/or in square pots. This is the perfect solution for reducing water and fertilizer usage, lowering room humidity, reducing weed growth, powdery mildew, algae and fungus gnats. Designed for flood and drain, NFT and other bottom-fed irrigation methods. They open up down the middle with a rear hinge and locks in place.