Airmax 510118 3/8-Inch-by-100-Foot Weighted Airline 3/8" Inner Diameter Airmax EasySet Weighted Airline remains on the bottom even when filled with air. No weights required. Flexible, durable and safer. It is now guaranteed not to kink, highly puncture resistant and is lead free. When runs are greater than 300 feet, larger 5/8" airline is required.