This is Dubro's E/Z Trimmer Master Set.

FEATURES: A trim tool that adds precision to your already familiar hobby knife!
          Works like a "straight-edge on a knife".
          Adjustable see-through trim guide with 4 trim sizes: 1/16" (1.5mm),
            1/8" (3.1mm), 3/16" (4.7mm), 1/4" (6.3mm).
          Quickly adapts for right and left hand use.
          Trim your covering accurately and quickly with this easy to use
            trim tool.

INCLUDES: E/Z Trimmer
          #2 X-Acto Knife Handle
          Four #19 Knife Blades
          Leading Edge Trim Guide
          Complete Instructions

SPECS:    Length: 5-3/4" (14.6cm)
                                                                   sdw 11/15/01
                                                                          ir/kh