Powerbox Mercury SRS & iGyro with GPS III Automatic Gain Adjustment 4110 Replaced by Mercury SR2 4130Powerbox Mercury SRS & iGyro with GPS III, which provides automatic gyro gain adjustment according to the model's airspeed. 4110 The PowerBox Mercury SRS is a new power management system which combines all the experience and findings we have gained over the last few years, together with customer requests, in a single compact unit. Never before has so much functionality been crammed into such a small space! The Mercury SRS is ideal for any application