Abstract: A utility knife/box cutter includes an ergonomically-shaped handle portion with exterior stippling to provide a good grasp upon the knife. Within the handle portion, a channel member is received in a forwardly extending cavity and movably receives a cutting blade carrier for longitudinal movement relative to the handle portion. A cutter blade carried in the blade carrier is moveable between a storage position entirely within the handle portion and successively further forward use and replacement positions. Also received into the handle portion is a spare blade holder member pivotal between a blade retaining position entirely within the handle portion and a blade releasing position in which a forward part of the spare blade holder member is pivoted out of the handle portion to present spare blades for removal and transfer to the cutting blade carrier.

Abstract: A utility knife/box cutter includes an ergonomically-shaped handle portion with exterior stippling to provide a good grasp upon the knife. Within the handle portion, a channel member is received in a forwardly extending cavity and movably receives a cutting blade carrier for longitudinal movement relative to the handle portion. A cutter blade carried in the blade carrier is moveable between a storage position entirely within the handle portion and successively further forward use and replacement positions. Also received into the handle portion is a spare blade holder member pivotal between a blade retaining position entirely within the handle portion and a blade releasing position in which a forward part of the spare blade holder member is pivoted out of the handle portion to present spare blades for removal and transfer to the cutting blade carrier.

Abstract: An improved, adjustable-blade safety knife of the type having a replaceable, single-edge blade slidably-retained within a single-piece handle against a keeper plate having a tang to engage the blade in a side-by-side assembly for protraction and retraction out of one end of the handle has planar guide member extending forward from the cutting end at one side of the knife at a controlled distance from the blade when the blade is extended and at a slight angle relative to the blade such that, when the face of the guide is brought into contact with the surface of a cardboard container, the blade is constrained to cut the side of the carton at a slightly inclined angle from the horizontal and along a line whose spacing from the container top is closely controlled, thereby preventing injury to the container's contents.