US Patent 6907668 Utility knife

A utility knife has a main housing half formed with a throughgoing aperture, having a face, and formed on the face with a peripheral annular array of transversely projecting hooks each having an outer end and a secondary elongated housing half having a face and formed with a peripheral annular array like the array of the main half of transversely throughgoing undercut holes opening at the respective face. The halves are engageable together at their faces with the hooks projecting into the holes and are relatively shiftable when thus engaged to lock the hooks in the respective holes. The secondary half is formed with an aperture like the aperture of the first half and directly aligned therewith in the assembled position. A retaining member snugly engaged in and through the aligned apertures holds the halves in the assembled position. A blade between the halves projects longitudinally from the housing halves.