This Multinautic wheel kit box includes one pair of sturdy 5 in. double rollers with mobile bases to create a boat or PWC mooring ramp. With 3 boxes, you can build a 2000 lbs. capacity ramp; with 4 boxes, you can build a 2500 lbs. capacity ramp. The more boxes you get, the longer and sturdier ramp you will be able to create to meet your specific needs. The bases wobble to assure a snug fit to the hull. Add a keel roller and a winch and you’ll get a small craft ramp system which is the most economical and safe way to protect your valuable investment. Have a look at the assembly guide for material list suggested to complete the project.