Basically what they said. But, the Green stykle bearings are more than most guys will ever need. GM's use the same style (ball rollers) and they take a ton of abuse. I have two G machine cars over 4000lbs that run road coarses, and the Greens are fine tehre too. The factory tapered bearings will never, ever wear out if properly maintained. Greens have a shorter life span. But, I've changed more stock bearings due to poor maintenance than I've ever replaced Greens for any wear of failure. I will say on my own car, they did fail..the seals dried out whilt it sat for a few years (more like 10+) adn the ebarings made noise. Having a better design that needs maintenance is sometimes not worth it, because nobody does the maintenance...lol.