Click on Wheels and Block

“Why didn’t I think of that?” is the immediate response of most parents and teachers to this simple and practical method of converting standard-size blocks (2¾” x 5½”) into wheeled vehicles. 2 rubber wheels on a metal axle, housed in a plastic frame, snap on and off in a jiffy. Unit block (5 ½”), 2 sets of wheels.

– 1965 Creative Playthings Catalog