I needed a pair of 45's during the early part of the virus imprisonment and stumbled on to a used (like-new) pair of Rogue/Hi-Temp 45lb bumpers for $0.60 per lb. They work great for my purposes combined with iron plates but if you had a mixed set of bumpers I guess the diameter could be an issue. My subsequent plate purchases have all been iron and US-made by Strength Co. which are outstanding.