fú​lì​tiáo​zhěng​bèi​xīn

buoyancy control device

  1. buoyancy
    the upward force exerted by a fluid (liquid or gas) that opposes the weight of an immersed object
  2. to adjust; adjustment
    to adjust, regulate, or restructure (e.g. a system, price, or organization) to suit new conditions
  3. vest
    sleeveless garment, such as a vest, waistcoat, singlet, or tank top