K Folded plastic with plastic slide

Data:

• Folder plastic with plastic slide
• Plastic special shaped cursor
• Tables and inch/decimal equivalents!!

Questions:

1. Name?
   Although the cursor is Seehase-like I think the main clue is the style of the table of Decimal Equivalents on the back of the slide. This and the simple construction strongly suggest it was made American maker Gisholt Machine Co., Madison, Wisconsin. David Rance
2. Purpose of small bulge at each side?
   Friction? Andries de Man
   When simple folded over plastic is used for the stock with a full-width plastic slide, sometimes such “small bulges” or something similar act a “brake” to ensure the slide does not too easily slide out. David Rance