The knife comprises a substantially hollow handle, a knife blade guided longitudinally movable in a knife blade guide track and at least one guided slider member coupled indirectly with the handle end of the longitudinally movable knife blade. A slider longitudinal slot which receives the slider member...http://www.google.ca/patents/US4805304?utm_source=gb-gplus-sharePatent US4805304 - Utility knife having a sliding blade holder
