Shell, 3" Naval Training Aid, Variable Timer W/ Spark Proof Wrench

Wonderful example of a genuine 3" VT fragment shell that was made into a training aid. Used in Gunner's Mate School to train gunner's on how to set the Variable Timing on these shells. Basically, the shell would leave the bore and the spinning centrifugal force would set the timer. The timer would indicate an air burst, just above the ground burst, or near vicinity of aircraft.  Very cool piece!