This is a genuine OEM part which is made for use with Flex edge milling tools. The roller ball assembly is secured on the bottom of the carriage housing allowing for easy movement. Over time it may wear out, get damaged or lost eventually requiring a replacement. Check the diagrams for your model to ensure the correct repair procedure. No...Read morete, it is made of high-quality materials and is sold as an individual item. You may need pliers to replace this part.