Original U.S. WWI Extremely Rare Inert Mk. I Defensive Grenade with Original Fuse and Lever Receivers and the "Niter Blue" color

and the "Niter Blue" color on top of the bolt release and magazine follower is still present

these were imported directly from Finland and bear SA (Finnish Army) markings but are undated

and one of its 4 screws are missing

Goodmans Fields

Original U.S. WWI Extremely Rare Inert Mk. I Defensive Grenade with Original Fuse and Lever Receivers and the "Niter Blue" colorOriginal Item. Only One Available. The Mk 1 grenade (sometimes spelled Mk I) is a fragmentation hand grenade used by American forces during World War I. According to its designers, it was to be the "simplest", yet most "fool proof", grenade ever made. However, some major problems appeared when the grenade was used in the field. It was retired from service before the war ended, replaced in 1918 with the improved Mk 2 grenade used through World War II.