Material: 6061 T6 Aluminum Finish: Black Anodized Length: 3" Width: 1.25" Height: 1.140" EGW's Chamber Checkers are machined from solid 6061 T6 aircraft grade aluminum. While some companies use boring bars to make chamber checkers, EGW uses the actual Clymer reamers that are used to chamber barrels. Anodized matte black for durability. Measures min case diameter. Measures max overall length. Mfg: Egw