The SmarteJack makes it easy to add retractable wheels to your dock or boat lisft. Once you add wheels (sold separately), you'll be able to efficiently move your boat lift or dock with ease. This retractable wheel kit includes a pair of aluminum posts that fit plastic wheels with 1-5/8" or larger hubs. For leveling, the jack adjusts up to 20" using a wrench or cordless drill. This patent-pending wheel kit fits most boat lifts. The one-time installation doesn't require tools.