I liked that it came in a pack of four for less than $8. My treadmill made a rattling noise. I did a little research and found out it might be a camp. I removed the rear roller and looked up the number on the existing bearing, googled that number and ended up with Revain. Ordered both rear bearings and replaced them in less than 20 minutes. And now my treadmill is working like new again. So happy!