This is the school version of M-79 grenade, and was made by the factory SRB(Slavko Rodić in Bugojno).
The grenade was used for training Yugoslavian people's army soldiers in techniques of throwing an
M-79 live grenade.
ŠBRK M80 is basically the same as
M-79 practice grenade, but the only difference is that ŠBRK M80 doesn't have any practice pyrotechnical charge.
The mechanism for opening the parachute from the grenade's handle can be used many times as it can be re-armed easily.
ŠBRK M80 has the same dimensions and weight as live
M79 grenade.
It has a painted yellow ring on its handle with black markings "ŠBRK M80".
The body of the grenade doesn't have any markings.

Scans and information thanks to Goran.