This is a high quality aluminum 1/4" spacer (outer diameter 5/8", inner diameter 5/16"). These spacers help close the gap between an LED Light Bar or LED Light Pod and a bracket, if there is not an exact fit. Purchase 2 spacers to accommodate a 1/2" gap (1/4" on each side). These fit best with an M8 bolt but can also be used for an M6 bolt.