Not much known on this grenade.
It was made of cast iron, and had a screw-on cover.
The cover had a hole in the centre to fit a safety fuze.
Filling unknown.

The left photo is the one I have in my own collection:
Length: 86mm, Diameter: 65mm
Weight (empty): 575gram.
This one is unmarked.

If anyone finds any documentation let me know.

Right photo © Luca Cossa.