The M1391A1 Detachment Percussion Device, 1 ea.
It's origin is unknown. Perhaps it was acquired from a unit that didn't post adequate security. Perhaps it was hand-made in another era and passed down with care from generation to generation. Perhaps a member found it in an attic amongst confiscated, er, um,... surplus cammie netting, flak jackets, and ammo cans.
Regardless of its mysterious and quite possibly illustrious history, the M1391A1 is traditionally rung after new members are sworn into the Detachment and on the Marine Corps Birthday. Some say it has been known to be rung in celebration for other special occasions, such as the Navy Birthday...
Ding-ding, ding-ding. 1391, arriving.