This is Jomar Products Battery Backer for Futaba J radio systems. This hooks between your receiver and dual batteries, and will activate your second battery if you lose voltage in the first one. FEATURES: Best insurance for fliers using two receiver packs. When main battery drops, this will automatically switch to the second battery. Works well with 4 cell, 5 cell, or Gel-Cell packs. Batteries can be different capacities, such as, 1200 and 600mAh. Warranty: Electronic Model Systems guarantees this Jomar product to be free of defects in materials or workmanship for a period of one year from date of purchase. INCLUDES: One Battery Backer with Futaba J connectors attached. One Instruction Sheet REQUIRES: Radio system and batteries. SPECS: CASE- Length: 1.53" (38.9mm) Width: 1.46" (37.1mm) Height: .78" (20.0mm) Weight: .8 ounces COMMENTS: Wiring- 6" servo wire with Futaba J connector and 2-5" wires with battery connectors. 8/18/01kzh ir/jl