BCD's Buoyancy Control Devices were not part of the original equipment for scuba divers but as the depth of the diving increased there was a need to offset the additional down force as you go deeper into the water as we do as modern divers.

As you can guess there are many different types of BCD knowing and talking to a Dive Pro will point you towards the dive jacket that will best suit your needs. This will be determined by water, depth and how many tanks that you will be bring with you for most dives a bag that has around 20 pounds of lift is going to suit your needs until you start to get into the technical diving where having a bag that can lift 75 pounds.