The item under consideration is known as a buoyancy compensator. The buoyancy compensator submitted, style ISLA, is a vest constructed of a flexible stretchable material known as BioFlex (U.S. patent #5,403,123). The material is cut, sewn and sealed to form an inflatable bladder that constitutes the vest. The bladder is inflated by a tube which extends from the back top of the vest , down the shoulder harness, to the diver’s front. The diver can either inflate the vest manually, by blowing into the tube, or can inflate the vest by attaching the regulator to the tube. The vest is equipped with a large exhaust valve with a pull cord that releases the air from the vest. On each side of the front of the buoyancy compensator is a pouch with hook and loop closures. The pouches are designed to hold weights that provide negative buoyancy while diving. By inflating and deflating the buoyancy compensator, in conjunction with the weights inserted into the front pockets, the diver is able to control his or her buoyancy throughout all stages of a dive. The exterior center back of the buoyancy compensator is molded plastic, shaped to cradle the compressed air cylinder. A heavy plate of plastic on the inside of the vest counter balances the weight of the compressed air cylinder when in place in the “cradle.” A heavy strap with hook and loop fasteners secures the cylinder in place. A carry handle allows for easy transportation of the buoyancy compensator and tank.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/965106