Precision Machined Shaft Collars All shaft collars in this pack have an exact 1-inch borehole diameter (internal diameter), an outer diameter of 1 5/8 inches, and a width of 5/8 inches. Please note that when used with shafts or inserts with an outer diameter of 1 inch, it’s expected that the fit will be tight. The shaft collars are standard-sized. This is not a machining error. Versatile Use Shaft Collars Whether you are a DIYer or a repair expert, these shaft collars are very useful in different types of machinery and equipment. Suitable for many applications in automotive, machinery repair, and even medical equipment repair. Common uses include wheel stopper/spacer, bearing faces, component locators, and more. From keeping shafts centered to ensuring that the wheels won’t fall off, these shaft collars are must-haves. Shaft Collars with Set Screws for Better Holding Power Bore shaft collars with set screws perform better than other types of collars, especially when used on pipes and axles that are of softer materials that the shaft collar. The socket cup-point set screw can directly secure the collar to the shaft. And unlike push-on retainers, shaft collars are adjustable and reusable.