The 1,000 watt Yamaha EF1000iS inverter generator is the ultimate in lightweight portable power. It is quiet and provides a "clean" source of electricity. The EF1000iS utilizes inverter technology with pulse width modulation control. Built with sound absorbing material and featuring a newly designed muffler on a revolutionary Yamaha MZ50 engine, the EF1000iS is both powerful and extremely quiet. A powerhouse performer at your fingertips.