Vanner - based in USA
Vanner was founded in 1977, producing electronics for use in ambulances, including what was claimed to be the first inverter in an ambulance.
Product Details
Inverters - A range of modified sinewave inverters with outputs of 300 - 2,600 watts
A range of pure sinewave inverters and inverter/chargers with outputs of 600 - 4,500 watts.
Location of Vanner website - http://www.vanner.com