The Air Chamber and Plunger Kit from Buyers Products works like a shock absorber that extends from the vehicle to the eye of the trailer's drawbar. It uses the truck's air brake system to reduce movement between the pintle hook and the eye or ring, and to lock the pintle jaw in place. Together with an Air Compensated Pintle Hook, the air chamber and plunger work to cushion shock and reduce wear. It's ideal for heavy duty applications such as semitrailers, both off-road and over-the-road. For off-road use, the load should be reduced by 25% and a swivel type trailer drawbar should be used.