The Piranha DPV is designed to be ready to dive in a neutrally buoyant configuration for both fresh and saltwater, right out of the box. To achieve this, each module is pre-weighted at the factory with lead shot for fresh water, and three stainless steel weight plates are installed with thumbscrews for saltwater. Each weight plate corresponds to a module of the complete DPV (019-7003 – Nose, 019-12009 – Tail, and 019-12010 – Battery). All Piranhas are shipped from the factory with all three weight plates installed, however please note that both the Battery and Tail weight plate are installed on the battery module. When diving the Piranha in a P2 or larger configuration in saltwater, simply leave both the Tail and Battery weight plate installed on the battery module closest to the tail, and remove the larger Tail weight plate from each subsequent battery module while leaving the smaller Battery weight plate installed on them. To configure for freshwater, remove all of the stainless steel weight plates from the DPV and reinstall the thumbscrews for safekeeping.