Share on Facebook The clamp that is used to hold plates securely in place on a barbell or dumbbell bar. The cylindrical metal clamps are held in place on the bar by means of a set screw threaded through the collar and tightened securely against the bar. Inside collars keep plates from sliding inward and injuring a weightlifter's hands, while outside collars keep plates from sliding off the barbell in the middle of an exercise.
