This listing is for an A.C. Gilbert erector set No. 10551, I believe from the 1950s or 1960s. From information I found, it appears that in the 1950s, Gilbert got computerized and started using numbering of their sets instead of like 12 1/2. The No. 10551 set is a particularly early and hard to find and came before the familiar red metal box these sets usually came in. It has been used but appears in good condition.. The motor was tested and runs. &nb...sp;There are no instructions. Box top is As Is, as it has been reglued and repaired on the corners. Also the cellophane is ripped and tore. The bottom of the box is still sturdy and in nice condition. Insert shows light wear. Please look closely at photos for details of what is included. Please enlarge and examine all photos and feel free to ask any questions that you may have.