Ocean Reef GSM MercuryGSM Mercury This unit is blending four different OCEAN REEF units into one: the extended range of the Gpower, the like stereo sound of the GSM SL, the clearness and double channel option of the DC and the battery life of the Gdivers. Features: Its foldable inside the mask. Now you dont need to assemble the comm unit and take it off the mask. Simply fold it close and pack the IDM. Brand new rechargeable, changeable battery with an autonomy of