The ATV 5th WHEEL dolly, fish house dolly, was built to assist ATV's pulling tongue heavy fish houses and trailers. When you lower the trailer on the the ball, the ATV will squat to a determined distance ( 3 to 5 inches or whatever distance you want ) to put enough down pressure on the ATV for traction. When you raise the trailer off the ball, the ATV will rise back up to its normal ride height and the ATV 5th WHEEL will be 3 to 5 inches off the ground for normal ATV operation. The ball height will remain approximately 19 inches at all times, hauling the trailer level. The ATV 5th WHEEL caster wheel is built with self lubricating brass bearings and an 8 inch tall, 3 inch wide, solid phenolic wheel, good to temperatures to - 45 degrees, load capacity of 2500 lbs and greaseable roller bearings. The ATV 5th WHEEL will fit in any 2 inch receiver hitch.