Both photo and scanned page provide by Stas. According to his documentation, this grenade was used in 1943 and 1944. The fuze was a design of Matti Saurio.
The grenade has the M41 stickgrenade warhead, but instead of the wooden stick with friction fuze, they have the friction fuze in the bakelite fuze body.
Different on this grenade, compared to the stickgrenade, is the screw-on cover that holds the fuze. This cover would not fit the wooden stick.