Yamaha Inverter Generator Parallel Kit for EF2200iS. With Yamaha’s TwinTech parallel kit, you can hook up two EF2200iS units for almost double the power output, while retaining the voltage and frequency of a single unit. Linking Linking 2 EF2200iS allows the flexibility to power more. When using for back up at home, link two of these for extra power. When camping, just take one to save on space, weight and fuel. The best of both worlds! Features: For use with EF2200iS. Close to double the power output. Retains voltage and frequency of a single unit. Linking provides more power.