The M17 is a cast iron grenade with a prefragmented ring over the middle of the body. It's an exact copy of the German egg-grenade of 1917.
Before use the safety cap had to be removed and the fuze had to be struck to a hard object to ignite the safety fuze.
The safety cap had a small mechanism inserted to prevent the cap from unscrewing by vibrations during transport.
This fuze model was used on most Yugoslavian grenades.

Length: 80mm, Diameter: 45/53mm.
Weight: 290gram
Filling: 20gram black-powder & aluminium powder.

Photos below © Josip.