The DuroMax Powerhouse Engines come in a few different HPs and types; gas, horizontal powerhouse engines and the electric start, gas, horizontal powerhouse engines in 3 different HPs. (The 7, 16, and 18 HP/HPE engines.). These options all come equipped with an air cleaner (dual, semi-dry, oil bath), and all DuroMax engines are produced with cast iron cylinder sleeves. Highly efficient powerhouse engines also all come with an E-Z Pull Recoil Starter/a Recoil Starter. Plus, the electric start engines are battery operated and come equipped with a key-switch box.