A regular key designated with the letter "B".
― In-game description
Key B is a mission item in S.T.A.L.K.E.R.: Call of Pripyat.
Description[]
It is one of two keys that must be acquired during the mission Bloodsucker Lair (the other being Key A) in order to open the container containing the Perin B3 gas. This key is found at the bottom of the ruined section of the Preobrazhensky Bridge in Zaton, inside a locker found in the wreckage of a car below the chasm. Inside the locker is also a copy of Internal order No. 423.