This practice rifle grenade has a body made of rubber and a tailpiece made of alloy.
The spotting head on top could be replaced for the colours shown below.
When used, these grenades were recovered and heads got replaced.
In case the tailfins got damaged, these could be replaced as well.
The grenade got launched with a propelling cartridge depending what weapon it got fired with.
Either the M1 Carbine or the FN FAL.

Length: 272mm , diameter: 75mm.
Weight: 650gram.

Photos thanks to M. Jochoms.