Check the listing for details. IST J-1700 Mercury Buoyancy Control Device (BCD) with Weight Pockets. Condition: Used. Listed at 99.00 USD. The IST J-1700 Mercury Buoyancy Control Device (BCD) is a compact and versatile unit designed for scuba diving. It is an X-Small size BCD with weight pockets included, offering ease of adjustment and optimal buoyancy control underwater. The BCD is suitable for water sports enthusiasts seeking a reliable and efficient buoyancy compensator unit from a trusted brand like IST. Whether you are a beginner or experienced diver, this unit provides essential support and functionality for your diving adventures.