Features + Benefits 4-stage air filter system for longer operating time Operating hours counter Protection against low oil level (Unit won't start if sensor detects low oil) Accessories available,sold separately: Wheel Kit,Item# 87835 4in. Wood Shoe Kit with 12in. extension,Item# 87843 4in. Wood Shoe Kit with 4in. extension,Item# 87848 6in. Iron Shoe Kit,Item# 87837 8in. Plastic Shoe Kit,Item# 87844 10in. Iron Shoe Kit,Item# 87838 11in. Plastic Shoe Kit,Item# 87839