This extremely robust, double-walled training buoy is primarily designed as a large surface buoy for freediving. It can also be perfectly used for marking during scuba diving or in any situation where a large buoy with storage space and carrying handles may be useful. Featuring a durable outer shell made of Cordura and a separate inner bladder made of polyurethane, which is sold separately. It has a large internal compartment, for example, for transporting the buoy line when not in use, with a zipper cover, four external handles, and two D-rings completing the equipment. It can be inflated by mouth or with an inflator hose and comes with a pressure relief valve. A stainless steel D-ring at the bottom of the buoy allows for attachment of the freediving line. Integrated flag.