The Swiss army uses some grenades to simulate incoming fire.
They were manufactured by Hans Hamberger AG.

Basically there are two groups:

Heulpetarden (“howling-petard”) which make a howling sound
Knallpetarden (“bang-petard”) which make a bang

Each group has four types:
-Without smoke (basic colour: black)
With red smoke (basic colour: red)
With yellow smoke (basic colour: yellow)
With blue smoke (basic colour: blue)
They are all cardboard constructions.
The handle is empty and at the upper end of the head is a cap.
Below the cap is a friction fuze (matchhead with a striker on a cardboard disc; 5 seconds delay).

Photos and information © W. Schumann.

Knallpetarde :

Length : 216mm
Diameter : 35/39mm
Weight : 105gram

Heulpetarde :

Length : 297mm
Diameter : 35/39mm
Weight : 154g

Below: Knallpetarde without smoke.