Ocean Reef GSM MERCURY - DUAL POWER (New!)The Ocean Reef GSM MERCURY DUAL POWER is an underwater wireless communication device built for scuba and diving applications. This model features two channels with channel 1 at normal power and a second mode with reduced power to help maintain sound clarity in confined waters such as pools. The result is dependable audio for group communication beneath the surface. Designed for rugged diving environments, the GSM Mercury Dual Power integrates with