Lock-Jaw HEX 50mm/2" Olympic Barbell Collar - Quick Release Barbell Clamp Extremely durable and light barbell collar. Fits all 50mm / 2" bars. GENUINE Lock-Jaw Barbell Collar. For home, commercial gyms, high schools and universities. Proprietary dual compound construction and unique design makes HEX extremely durable but also very lightweight. Holds plates secure and protects bar finish. Fits all 50mm / 2&#034; bars. Designed for all lifts including Bumper Plates, Olympic-Style and Powerlifting.