Rapidovka grenade was produced in the factory RAPID in Virovitica, Croatia.
This factory was local ironwork industry. Just as many other croatian factories with iron and steel working-machinery at the beginning of the war in 1991,RAPID ironwork started to produce grenades for Croatian army. The grenade is called RAPIDOVKA amongst croatian soldiers.

It was made of cast iron, in two separate parts of the body which were brazed together after being removed from the mould.
The engineers from RAPID factory decided to use the simpliest fuze mechanism for this grenade. There was no time and resources for making any improvised complex fuze mechanism, 5 cm long pyrotechnical slow-burning fuze with detonator No.8 on it's end. From the internal side of the grenade's body neck the thread was made for screwing metal cap which was 24 mm in diameter.That cap was drilled on its centre with 5,5 mm hole in diameter,and pyrotechnical slow-burning fuze with detonator went through that small hole.The metal cap was made of steel or sometimes of brass.
The grenade was filled with 60 grams of Amonal or Vitezit.S ome of the last produced grenades were even filled with plastic explosive(Vitezit V20).

All info and photos below © Goran.

Rapidovka grenade was produced in three different variants, with differences in fuze and in colour of the grenade's body :

-first variant(RAPIDOVKA 1)was fitted with about 5 cm long pyrotechnical slow-burning fuze and detonator No.8.The first grenades of this type were painted in red anticorrosive paint.The factory had some cans of that anticorrosive red paint,so they used it for painting first grenades of this type.That was at the beginning of production,but later RAPIDOVKA grenades were default painted in green or sometimes in black colour.

-second variant(RAPIDOVKA 2) was fitted with croatian made percussion fuze,the same as the fuze used on RB BRON 1 grenade.The body of the grenade was the same,just other type of the thread was made from internal side of the grenade's body for fitting that impact fuze.This variant of grenade was painted in green or sometimes in black colour.
-third and the last variant(RAPIDOVKA 3) was fitted with practice fuze for yugoslavian VBR M-75 grenade,but with removed practice detonator,and fitted with improvised croatian made detonator.That was the same type of the fuze as on JASKANKA 2, JASKANKA 3 and TTM grenades. Body of the grenade also had different type of the thread made from internal side of the grenade's neck. These threads were standard type for screwing practice M75 fuze. This variant of RAPIDOVKA grenade was painted in black colour.

Total length : 90mm (body)
Diameter : 65mm
Weight : 550gram
Filling : 60gram TNT or Nitropenta or Vitezit or Amonal.
Fuze delay : 2 - 3 seconds.

It is very interesting that the mould for this grenade was also sent to the OLT factory in city Osijek, Croatia. And OLT was producing the same grenades as RAPIDOVKA1 and RAPIDOVKA2, they were called OLTOVKA 2 and OLTOVKA 3.The only difference was that both of them were painted in some kind of olive-drab paint, not green or black, and OLTOVKA 2 was fitted with longer piece of pyrotechnical slow-burning fuze (about 10 cm long).
Also the same grenade was produced in city Zenica in Bosnia for Bosnian army. That grenade was produced in Metalurgic institute in Zenica,Bosnia. It was unpainted and fitted with the fuze for M52P3 grenade(the same as M75 fuze but with reverse thread).It is unknown how that mould for RAPIDOVKA grenade made in Virovitica, Croatia ended in Zenica, Bosnia.