Hot Head PRO4 Engine Heater is design to provide the fastest heating rate using a single 110v plug. We used our Low-mass, Low-volume, on-demand technology to join the trend to offer the best unit for use with limited power. We tested and fielded units that proved to be adequate for 4 cylinder automotive applications. Realize the heat output (for 110v@15A) is about the same as a hair dryer For large engines, say a V8 it a non-alternative to our more powerful PRO unit. Regardless, the Hot Head PRO 4 out-performs any 110v unit in the U.S. the market. It is not offered in world power option.