Wm.F. Drueke & Sons, Grand Rapids, 4, Mich.
(plastic puzzle with 31 tiles 2.9" x 5.1" x 1/4"; directions on the back)

With a computer in 2011, M. Keith identified 299 solutions using valid Scrabble words with the stronger requirement of having no two-letter words; 14 of them use only the first 7 columns (M. Keith [2011], "Vintage Plastic Sliding-Letter Puzzles" Word Ways 44:4, 310-31; see also M. Keith [2012], "More Sliding-Letter Puzzles").