Patent ID: 7930829

Claim:
A knife comprising: a handle; a handle extension connected to the handle for movement relative to the handle between first and second positions, the handle extension being constructed and arranged to be disposed forwardly of the handle when in the second position; a utility blade carried by the handle extension, the utility blade having a mounting notch formed in a first linear edge and a cutting edge opposite the first linear edge, wherein the utility blade substantially has the shape of an isosceles trapezoid, the cutting edge being disposed on a longest edge of the trapezoid; and a manually movable slide button, wherein manual movement of the slide button slidingly moves the blade between exposed and stored positions, wherein, when the handle extension is in the second position and the blade is in the exposed position, the knife is in an operative position in which the utility blade is locked to the handle extension, wherein a closed length of the knife when the handle extension is in first position is less than 5 inches, wherein the utility blade is detachably carried by the handle extension, wherein the knife further comprises a manually operable blade retention lock disposed on the handle extension, the blade retention lock being manually movable between a locked position, in which the lock keeps the blade connected to the handle extension, and a released position that allows the blade to be manually disengaged from the handle extension, wherein the entire blade retention lock is movable with the handle extension relative to the handle when the handle extension moves between its first and second positions, and wherein the blade retention lock comprises a protrusion that engages the mounting notch when the blade retention lock is in its locked position, but does not engage the mounting notch when the blade lock is in the released position.