Review on Electric Sealed 6203 2RS Bearings by Donepart by Dave Mosby

This replaced two completely destroyed rear crank bearings on a Sunny Spin Bike model SF-B1877. This is the same "model number" as the warranty parts. They were easy to install and worked great. Not sure about durability as I just replaced them. I'm glad they came in a pack of four though. It should be noted that if you're swapping out bearings on a spin bike, you'll need two of the four, not one, so keep that in mind.