M1 Carbine USGI 15rd Magazine, original US military, unissued.
It's a little dismaying that they are listed as rusted but could likely be cleaned to be functional. The price slays me. They used to be a couple of bucks.
Thanks for speaking well of my Underwood. It is original but is worn. My dad's gun is the nice one for use as a reference for how the M1 Carbines originally looked.