Gun Bore Gauge, Brass tapper type gage

Gun Barrel Bore Gauge;

Made of Brass; Used to check the Caliber of the barrel mizzle. 

Gun Accessory, See at a Glance the Caliber, useful for many Shotgun-Gauges 

Made of Brass w/Key Chain Hole Easy to Use  

Check Caliber Barrel Bore Diameter at Muzzle, nice Gun Accessory to have.

Also includes a mm diameter reading, Over all length is about 3-1/4" long