U.S grenade

[chuck303]

I picked this up out of a collection. Very nice overall.

[BlackCat1982]

I don't recognise the fuse assembly, the ordnance experts will opine but it doesn't look like any I've seen before.

[spotter]

US mk1 fragmentation grenade and if i got this right it was introduced into service in 1917 and due to problems phased out in 1918.
Quite a bit of info here on inert-ord website
American Hand Grenades, WWI - Inert-Ord.Net

Im sure tek or vegi will be able to provide more
information when they see your post

[chuck303]

I was able to review some information here about this type