not sure what happened with the others guys part that made him this part 1 star. worked just perfect for my XJ. i have a 3" RC lift with 31" tires so i was running just about 6 mph over the limit when traveling at 60 mph. this calibrated my speedometer just as expected and i could never be happier. now i can figure out when to do my oil changes without the math.Quick and easy install, took my about 20 min (followed a youtube video). i purchased the gasket for this, but didnt bother installing it, although i may regret that later. so far no leaks though.all in all, i recommend this product to anyone who wants there speedo to be calibrated correctly.