These tubes are not for everyone however, they are for the adventurous & experienced tubers. Summer floating in a lake, rushing down a river or lounging in a pool. These tubes are perfect for hard play or relaxation winter snow tubing in your back yard, off trail or the local sled hill. These are not wimpy tubes that pop; they are the real thing, durable & tough protected valve stem small rubber safety valve cap protects from pokes & scrapes summer tubing tips be sure to inflate inner tube to proper size for better floating experience. Covers are not required but do add protection from scrapping on river or lake debris to inflate once tube can stand, use the start/stop method; fill with small burst of air then stop air flow, continue until full size is reached. This keeps the tube round. The tubes outer diameter increases the center hole decreases. Tube must be firm to the touch. Under-inflated tubes won't float well to deflate use a valve tool (sold at auto stores) to remove the valve core. Re-insert core; seat it tightly to avoid leaks tube sizing small: 32"fits 120 lbs. or less. Medium: 36" 120-150 lbs. Large: 40" fits 120-175 lb., X large: 45" fits individuals up to 280 lbs. our largest 68" tube is for fun on a lake.