Eliminate trailer bouncing and control sway on tandem axle 5th wheels and travel trailers. Most travel trailers and 5th wheels don't have shock absorbers simply because there isn't room. Roadmaster Comfort Ride heavy-duty, nitrogen-charged shock absorbers feature patented, adjustable mounting brackets that eliminate space constraints, allowing the shocks to be mounted vertically, where they have the leverage to limit up-and-down motion on both compression and rebound. They eliminate trailer bouncing and "porpoising". To determine your fit, find the diameter of your trailer's axle and the weight rating. Both are found on a sticker on the axle. For best ride quality, install Roadmaster's Comfort Ride Slipper Spring System (sold separately) with Comfort Ride Shocks. Made in USA. Comfort Ride Shock Absorber and Slipper Leaf Spring Systems significantly reduce the cause of these common symptoms: Chucking- the truck is rocked forward and aft when the trailer goes over uneven pavement (dips, frost heaves and bridge expansion joints).Axle roll-up- during braking, the trailer's rear tires are lifted enough to cause a loss in traction (and a rise in the driver's blood pressure).Suspension rebound- when one tire goes over an obstacle, the trailer tips sideways. After the tire clears the obstacle, the leaf springs (and the trailer with them) rebound like a pogo stick.