The Rugged Radios PLUS2-H28 rear-seat expansion kit takes a two-person Rugged intercom setup to four seats. This configuration pairs Offroad Mono cabling with AlphaBass over-the-head (OTH) headsets for the two rear seats, with 16 ft intercom cables that reach the back of the machine.What the AlphaBass headset bringsThe AlphaBass over-the-head headset features true carbon fiber, a Flex Boom mic with M101 Red dynamic noise-cancelling element, leather ear seals, and easy-reach volume and bass controls — rich rear-seat audio without a helmet.CompatibilityThis Offroad Mono configuration is for Rugged MONO intercom systems. The PLUS2 family also offers STX Stereo configurations for STX Stereo high-fidelity intercoms, plus helmet-kit versions — pick the configuration that matches your front-seat system.Specifications Expands a two-seat Rugged intercom system to four seats Configuration: Offroad Mono cabling + AlphaBass over-the-head headsets 16 ft intercom cables reach the rear seats AlphaBass: true carbon fiber, M101 Red noise-cancelling mic, leather ear seals, volume and bass control Includes the rear-seat headsets and 16 ft intercom cables for two rear positions.