Hardwood frame, slotted to receive blade. Blade adjustable to cut 3/4″ slot. Fastened to frame with two nickel plated screws. Blade 1-5/8 inches deep. Lengths, 6 and 8 inches.
A stairbuilders or dado saw. Many stair/dado saws were made from American beech, but I’ve seen a few from maple, apple, and others. I’d like to see an example from this era to determine the wood in use.