This famous small grenade was developed and constructed in The Netherlands, but never made it into the Dutch army.
It was in use with the US army and others.

Length : 58mm
Diameter : 40mm
Total weigth : 140gram
Filling : 36gram Comp. B

The two scan below show the original factory folder for the V40grenade ánd its launcher-attachment.

The photo on the right shows the practice V40 fitted to the rifle grenade adapter as shown in the factory folder above.

Photo © Cory.

And another type of adapter, I think US made.

Photo © Siegfreid.