This defensive grenade was made of cast iron with a pressed steel plate, fixed by screws, on one side.
Inserting a finger into the cap secures the striker so that the safety could be switched.
After releasing the grenade, the cocked striker would hit the primer, fires the delay resulting in detonation.
Duds occurred when the finger did not release the striker fast enough, the striker would not hit the primer hard enough..
Largest diameter :
Smallest diameter :
Width :
Weight 65gram including 28gram trotyl.

Above on the right and the two photos below show the throwing dummies that were used.
Below left represents the old model with thumb safety in the middle.
The right photo shows the dummy for the newer type.

Scan above and photos below © B. Bosman.

Bernt's scan shows the instruction leaflet on the "Model Grootendorst" which used a thumb-pressure safety in the center of the body.
This was the first "dooshandgranaat" type.