 These back-up guns are usually smaller in size and caliber than the main weapon and most are suitable only for close-range self-defense.Some law enforcement officers keep the back-up gun in a different location than their duty gun or in a location that is well-concealed (e.g., in an ankle holster or in a holster in the small of the back), so that even if they have their duty handgun taken away by an armed perpetrator, they will still have a gun.Guns used as police back-up guns include