OSO Pro Barbell Collars - Pair (Purple) Sold in Pairs - Made with 6061 Billet Aircraft Grade Aluminum Construction Innovative design & all new locking mechanism - Superior durability - Fast locking action Fits all 2" olympic bars - Lightweight - Will not damage plates or bars Weight .4 lbs per collar - Made in the USA OSO Barbell offers a 2 year warranty on the locking mechanism.