Here we have two versions of the Sterling Plastic Pencil Box. The ones on the left are the Multiplier Pencil Box #555 and the ones on the right are the Pencil Box #524. As you can see if you click on the picture that some had advertising on them and were probably given away to customers. The boxes had a pencil sharpener, 6" ruler that doubled as a sliding lid, and two or three pencils. The most popular is the Multiplier Pencil Box and had a plastic slide for use in multiplication.