Abstract: A knife having generally thin, relatively inexpensive and replaceable blades which can be extended from the handle when the knife is to be used and can be retracted when the knife is to be stored, the knife having a cavity in the handle for receiving a stack of the blades, a slide having a magnetic face for engaging and sliding the innermost blade into extended position and for retracting the blade into the handle and a lock for locking the blade extended.

Abstract: There is disclosed a multi-layer tape system, of the type disclosed is Castelluzzo application Ser. No. 930,700, U.S. Pat. No. 4,182,789, for applying register marks or other symbols to aligned art-work sheets used in the graphic arts field. In a two-layer system, each of two superimposed tapes has aligned markings thereon. A weak adhesive secures the two tapes together, and the two outer surfaces are coated with a strong adhesive. In a four-layer system, a separator is disposed between a pair of two-layer systems; the separator has holes therein so that the two tape systems can adhere to each other and remain in alignment, contact being made in the regions of the holes. The relative adhesive strengths maintain the system integrity prior to use while also permitting tape sparation during use. Instead of using clear tapes and printed markings as in the Castelluzzo system, opaque or colored tapes with punched markings are employed.

Abstract: There is disclosed a multi-layer tape system for applying register marks or other symbols to aligned artwork sheets used in the graphic arts field. In a two-layer system each of two superimposed clear tapes has aligned markings printed thereon. A weak adhesive secures the two tapes together, and the two outer surfaces are coated with a strong adhesive. In a four-layer system, a separator is disposed between a pair of two-layer systems; the separator has holes therein so that the two tape systems can adhere to each other and remain in alignment, contact being made in the regions of the holes. The relative adhesive strengths maintain the system integrity prior to use while also permitting tape separation during use.