A 4 gauge indirect sprue with runner bar. The diameter of the runner bar is .23” / 5.6mm, so this would be the recommended size for non-precious alloys. This sprue is made from a special wax, so by warming the sprue slightly (holding it in your fingers), it can be bent and will hold the shape. This sprue has a button on one end that plugs into the base former on most ringless systems with a hole diameter of .336” (8.5mm). Packaged 250 to a box. Made in the USA.