Unknown Russian Grenade?

[ron3350]

I have this unknown grenade from the same source as the Lishin I posted. It also has a reproduction handle. I hope it was not a fuzed, finned type of grenade?
The steel head is 725 grams (1lb 9.5oz) , 60mm diameter, 159mm long body and 178mm with alloy nose plug. About 240mm overall steel grenade length without handle.
The nose plug has a leather washer and there is a hole in the stem for a safety pin? that maybe went through the hole in the striker pin?
I have no idea of the ID but assume it is Russian so any info is welcome and looks WW1 vintage.

 

[MINENAZ16]

I already saw this grenade on other russian forum.
Seems to be a ww1 russian grenade made in Latvia (no more information).

 

[ludokhan]

a sight of the mention in the field, it would appear that this is produced at RIGA