K-tool
The K-tool is a tool used by many fire departments for forcible entry.[1] It is used in conjunction with a Halligan bar and a flat-headed axe or maul (commonly referred to as "irons" or (with a maul instead of an axe) "strong irons") to remove a cylinder lock. It consists of a steel block roughly 3 inches by 3 inches by 1 inch thick with a K-shaped notch on one side, having sharp edges that grip the cylinder, and a U-shaped flange on the other side. The notch is slipped over the lock cylinder, then forced down by striking with the flat side of the axe or maul. The halligan is then inserted into the flange and used to pry the K-tool off the door, thereby pulling the entire key cylinder out. The bolt is then retracted from the inside of the cylinder hole using a turning tool, such as a screwdriver.
Some cylinder locks include additional shields (outside and internally) that will make this type of entry more difficult and time-consuming, and there may be additional (non-cylinder) locks to deal with.
The K-tool can be used on most styles of door, although it is often faster to use the irons (combination of an axe and halligan tool) or a hydraulic ram on a solid door. The benefit of a K-tool comes where it is impractical or dangerous to break the door, for example, the large plate-glass doors in front of a commercial building will quickly yield to a well-placed blow from an axe, but may send fragments of glass flying, and will result in a pile of broken glass. The K-tool can be used to pull the core from the lock without damaging the door itself. The K-tool is also useful during investigations where no fire is readily evident. The core can be pulled from a lock, which can often be repaired at lower cost than replacing a door and jamb damaged by other, more energetic entry methods.