The high altitude carburetor kit includes carburetor jets and carburetor seals for operation at altitudes above 2000 feet above sea level. The high altitude carburetor jets fit the 224cc Onan 4500i generator engine. As altitude increases, the amount of oxygen in the atmosphere decreases by approximately 3 percent for every 1000 feet in elevation. The factory installed carburetor jets perform best at altitudes below 2000 feet. Above 2000 feet, the fuel-to-air mixture becomes too rich. High altitude jets provide the right mixture of fuel and air.