I think the case is sterling silver because it does not react to a magnet, but I couldn't find a .925 silver stamp to verify it. The style is similar to vintage Cartier style card holders but there is nothing on the box, nor the insert that shows it was made by Cartier for IBM.
The case weighs about 2 1/2 ounces. It is a little less than 3 3/4" long and a little more than 2 1/4" wide. I polished the outside but not the inside of the case. It includes the original box and the black cloth case holder.
It was never used.