Alliance Hole-Less Hydro:Utilizes two jacks, one on each side of the car. Single stage jacks are used for travel up to 14 ft. Two stage jacks are used for travel up to 30 feet. Pros: The jacks are located above ground, eliminating the need to drill a deep hole. This also reduces the risk of oil contamination. Cons: Restricted to a 2 to 4 stop applications. Also, the hoistway width requirement is slightly greater than in-ground elevators.