dont know much about these,but i have 3 of them two are the same and one has a slightly bigger opening
dont know how much they cost new ,but you can have all 3 for $50 shipped
three tz bearing the one without center insert is for a billet 10mil crank,other two fits any crank and they are like new.
i removed them because i dont use tz bearing...only regular or max load when i build
$45 for all