My latest pedals that I purchased for my MTB that I no longer have but do have the pedals on my old Giant RB now because I like them so much are Rock Bros 4 bearing platforms. They basically have 4 'polymer sleeve bearings' and after a lot of abuse and use are still as smooth as a baby's butt and are still my favorite pedal. They can be taken apart and serviced just like regular old steel ball bearing, but when your bike is in mud and water a lot they will never rust. The sleeves do have rubber seals on the ends and a preload requirement just like ball bearings. They are not LOW END pedals just because they have 'polymer bearings'