The raze quick lock collars are made from a strong plastic to make sure that they last one of the best features about these collars is they are silent when putting onto the bar these are also simple to click on for secure use on a 50mm bar and then they come off just as easy thanks to the cleverly designed clip ensures complete piece of mind while using an olympic bar that the weights will not come off key features of the raze quick lock collars ideal for securing olympic discs onto a 50mm