Power Systems Husker Power Locks, Compression Barbell Collars for Olympic Bars, 2-Pack, Black (50465) Compression locking offers superior holding power Nylon bushing prevents damage to the bar 2 inch diameter collars for Olympic size bars Collars lock quickly and release easily Weight training accessory for speed, agility, strength, power, running, football, volleyball, basketball, baseball, soccer and all other athletic, fitness, weight, or cross training