A timer based explosive that attracts creatures by using high frequencies.
The B.O.W. Decoy is a special grenade that appears in Resident Evil: Revelations. They were manufactured as early as 2005. Upon throwing a Decoy, it will emit a sound that attracts certain types of B.O.W.s and will explode after a short period of time. They attract everything except Hunters and Scarmigliones.
Once a group of creatures are gathered around a Decoy, you can either shoot the Decoy and destroy the monsters or you can kill off stray/on-coming enemies that are not yet attracted to the explosive.
You can throw two or more Decoys simultaneously and cause a bigger and stronger explosion. This strategy is also effective with regular grenades.
Only BSAA operatives are in possession of Decoys, making it a possibility that it was designed and created by the BSAA.
You and your partner will never take damage or be killed by an explosion from grenade-type weapons. However, a Shock grenade can stun you and your partner temporarily if you're caught within the blast radius.