A canister of a dangerous chemical nerve agent.
― In-game description
A canister of Perin B3 gas is a mission item featured in S.T.A.L.K.E.R.: Call of Pripyat.
Description[]
The Perin B3 is a nerve gas that was supposed to be tested in the Zone. The convoy carrying it however crashed on the Preobrazhensky Bridge, with the crew presumably either killed or left it behind after the crash.
The Perin B3 is featured in the Bloodsucker Lair mission, where the player must use it to clear out the Bloodsucker Lair underneath the Krug Antenna Complex. It is found in in Zaton, on the Preobrazhensky Bridge in a locked container on a truck. The gas can be accessed as soon as the game begins, although its location is only given by Owl for 2000RU. Two keys are required to unlock the container, both of which can be found in lockers in the crashed UAZ-469 wrecks.
The Perin B3 weighs a heavy 10kg. Strangely, unlike most mission items, this one can be dropped at any time. This may be because the canister can be obtained at any time by the player regardless of mission status.