Blue Demon BLUEARC-90STI 90-Amp Inverter Style Stick and Tig Welding Machine The Blue Arc 90STI inverter-based stick welder with TIG option features 115V inverter technology that can be used almost anywhere. The inverter-based system offers increased power output from a smaller transformer, resulting in an extremely lightweight. This Inverter stick includes a shoulder strap. It is ideal for welding all sorts of carbon steel, stainless steel, cast iron, and hard surfacing.