An actual military issue 30mm shell casings that was fitted with a plastic projectile head.  These are now completely inert and used in the guns on the A10 Warthog. A great desk item the  tops can also be popped out and casing and used for any kind of "secret stash".  These 30mm shells have 4 drill holes towards the bottom of the so the shell and cannot be reused. 

Features & Specs

• Inert Ammo 
• Measures approx. 10 1/2' H x 1 3/4" D
• Removable Top for “Hidden Storage” 
• Dummy ammo can not be shipped out of the U.S.
• Novelty Desk item