Developed by the Dellenbarger Machine Company of New York City for use with 60mm, 80mm and 4.2" mortars, this device allows for crew training with reusable projectiles and inexpensive blank cartridges. The body of the device is a tube insert, 26 3/4" long with a 1" muzzle diameter, a striking anvil set into the base, and a series of C-clamps and bases for centering it in a larger tube. The projectiles measure 5 1/2", and use a pair of 22 Short blanks in operation; the "propellant charge", which faces rearward and is fired by the anvil to propel the round, and the "spotting charge", set off by an inertial firing pin on impact to indicate the point of hit. Twenty of these projectiles are included with the kit, along with a National Guard marked green painted hardwood case, cleaning tools, and more. Case is serialized no. 1983. Excellent