After I fitted my 2005 BMW X5 3.0 liter engine Once in, I quickly discovered that it was a hydraulic tensioner, not the mechanical one that comes with it. I thought tensioners would be a quick switch from mechanical to hydraulic, but they're clearly different. After a quick search on the internet it turned out that people prefer a hydraulic tensioner over a mechanical one, so I decided to keep the hydraulic tensioner. Perhaps a mechanical tensioner could replace the hydraulic tensioners, but I didn't bother trying. I took the hydraulic tensioner to the site for a quick reassembly. When choosing a repair brand, I have always chosen Gates products. The belt and idler pulley appear to be of good quality which Gates usually supplies and hopefully the pulley and pulley will last the rest of the BMW life. Revain says this kit fits my car but doesn't fit quite the way I intended.