Lyman Pro Single Ammo Checker 300 BLK Silver. Simply drop your loaded cartridge into the gauge and if it fits it will chamber in your gun. A "must" final check for competitive shooters. Specifications for Lyman Pro Single Ammo Checker: Manufacturer: Lyman Fabric/Material: Stainless Steel Weight: 0.2 lb Color: Silver Features of Lyman Pro Single Ammo Checker Precision machined from corrosion resistant stainless steel for a long rust-free life Outside flats prevent rolling O-rings provide a non-slip grip Package Contents: Lyman Pro Single Ammo Checker Lyman 7705201: Pro Single Ammo Checker 300 BLK Silver