41-B-302 Extension ¼” Drive – Walden 3121. The specifications are for this extension to be 2-1/2" and this one is 3" but it's the only Walden short 1/4" extension offered in the wartime catalog and this is the only one I've ever found in the many Walden sets that I've collected. This extension did not come in any set but was offered individually. I would certainly like to find another! The markings are very faint on this tool but the part number can just be made out.