I replaced both rear air springs on my 2015 Hyundai Equus Ultimate. To be honest, I was hesitant to buy this product. However, so far so good. The springs were easy to assemble and both filled with no problems. Also, the ride is smooth and I can't tell these springs apart from the factory springs that I replaced. I'll be releasing an update in a few months, but for now I'm hooked and have saved a lot of money.