I don't know exactly when this one was designed, but must have been at the end of the war.
Date on the photo below says 1944.
The body is made of a magnesium alloy, the fuze and filling plug are both magnesium.
Cap had to be removed and the fuze had to be struck to a hard object to ignite the 5seconds fuze delay.
The grenade was not taken in use with the armed forces.

Diameter: mm, Igniter: T-14
Weight: 354gram including 198gram RDX