Abstract: A double-edged utility knife for carpet installers, roofers, glaziers and sheet rock workers has a two-part handle. The handle clamps a detachable reversible double-edged blade at a transverse angulated position with respect thereto. Vertical cuts can be made in tight corners without applying excessive force. The transversely angulated knife blade affords access permitting vertical cuts in tight corners. During cutting the user's hands are displaced from the cutting line, and kept from being inline with the cutting blades. Operation-induced injuries are virtually eliminated. The double edge blade is provided with a geometry especially well suited for wallboard, roofing, carpet cutting/glue scraping and glazier use.

Abstract: A single use self-contained surgical knife provides twist stability and lateral support for the knife blade. Turning a knurled ring member within the containment casing retracts the knife blade into the containment casing. Retraction of the blade is permanent; once retracted, subsequent usage of the knife blade is prevented. A substantial safety margin is provided, in that injuries occasioned by the retraction process are virtually eliminated. The knife blade remains forever in the retracted condition, preventing spread of blood borne infections such as AIDS, Hepatitis and the like, that might otherwise result from subsequent usage of the knife blade.