Hydrofarm Active Aqua AS4RD Round Air Stone, 4 Inch This active aqua 4-inch air stone disc is a great way to add oxygen to your hydroponic growing system. The micro-pore design energizes your growing solution as it aerates and circulates your nutrients. It will extend the life of your nutrient solutions, help keep your roots healthy and promote exceptional growth. This product weighs 0.5-pound. Measures 6-4/5-inch length by 4-4/5-inch width by 1-inch height. Features Active aqua 4-inch air stone disc is a great way to add oxygen to your hydroponic growing system The micro-pore design energizes your growing solution as it aerates and circulates your nutrients It will extend the life of your nutrient solutions Help keep your roots healthy and promote exceptional growth Measures 6-4/5-inch length by 4-4/5-inch width by 1-inch height USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.