This self sinking air hose is designed to sink to the bottom of your pond without additional weight. It is 0.650 inch (approx 5/8") inside diameter and 1.2" (approx 1-1/4")outside diameter. The black color easily disguises it on the pond bottom. You may purchase it in 1 foot increments or 100 foot rolls. Use a 5/8 in. barb to conect to your diffusers.