I ordered #630s of Vulcan Alpha bumpers, 24kg & 16 kg Absolute Training Kettlebells, and two sets of the Olympic Bar Compression Collars. After two weeks of use from my wife and I, the Vulcan Alphas are everything they claim to be. Low bounce, low odor, quieter than the competition, approved for outdoor use and not as thick as the competitions. The #10 plate has a smaller diameter than the rest of the bumpers and Vulcan clearly states this up front. The #10 and #15 bumpers are rock solid. I also have a set of #10 olympic diameter technique plates from another manufacture and when compared to the Vulcans, the Alphas are clearly quieter. Near to nonexistent on odor on the Vulcan’s. Its ever so subtle that it’s not really noticeable. I bought nine horse mats about two months ago and the mats clearly overpower the Alpha’s new. For $55 the Olympic bar compression collars were clearly the right choice. IMHO, other collars within +/-$20 price range are not competitive to the quality you’re receiving. Rock solid in performance. Details like laser etched engraving. Nice.