Hornady has been making quality reloading equipment and components for over sixty years. The Lock-N-Load Overall Length Gauge Modified Cases are no exception. These gauges are needed to measure the bullet relationship to the lands of a barrel when being used with the Hornady Lock-N-Load Overall Length GaugeSpecifications:- Fits: 300 Remington Ultra Magnum (RUM)- Material: Brass Case - Quantity: Package of 1