Ivanko (COT-2.5 Compression Ring Olympic Training Collars, Chrome (Pair)COT-2.5: Compression Ring Olympic Training Collar. This pair of collars fits 50mm Olympic bar sleeves. If you want a durable pair of weightlifting collars that will hold the weight, that are easy to use, these are the ones you want. THESE COLLARS **DO NOT FIT** "Regular" (AKA "..