For the Zero Gravity Sidemount System, Halcyon offers you a Spine Weight Pouch to add extra weight should you need it. The weight pocket holds 15 lb and fits on the inside of the Halcyon Zero Gravity SM Harness.
This way, you can upgrade the Zero Gravity BC System to Dry Suit diving, if you wish. The pouch sits comfortably down your spine. This pouch is very suitable for travelling as well, same as the BCD.