Bluewater Off/On Combine Battery Switch w/o Base - Surface Mount - Red [9800-011-11]Off On Combine Battery Switch without Base Surface Mount Red The Dual Circuit Plus switch builds on the standard dual circuit configuration by adding an emergency parallel function. This allows both circuits to combine instantly in the event of a start battery failuredelivering backup power when you need it most. Smart Power Management Provides secure isolation during normal operation Emergency parallel mode ensures dependable backup starting power