Original U.S. WWII M21 Inert Practice Pineapple Fragmentation Training Hand Grenade with M10A2 Fuze Antique Shotgun This design features a fiberglass

This design features a fiberglass body

and although the attempted rescue failed

The UDT assisted in clearing mines in Wonsan harbor

with the plating showing some wear and oxidation

The interior retains some of the original internals

Original U.S. WWII M21 Inert Practice Pineapple Fragmentation Training Hand Grenade with M10A2 Fuze Antique Shotgun This design features a fiberglassOriginal Item: Only One Available. Totally inert according to BATF guidelines with a hollow body and inert fuse. This is a great example of the M21 Practice Training grenade, an inert version of the iconic U. S. fragmentation pineapple grenade issued during WWII. The Mk II was standardized in 1920 replacing the Mk I of 1917. It was phased out gradually, the U. S. Navy being the last users, and on 2 April 1945 the Mk II and Mk IIA1 were re designated