Jacobs style drill chucks with very fine jaws, can hold the smallest of drills, open up big enough to hold 3/8" drill. Comes with matching chuck key. 3/8"-24 UNF threaded mount.

New old stock, never used, still covered with preservative grease and with wax paper stuck on in places. See pictures.

Mall was an American power tool manufacturer in the middle of the last century. Apparently they had some parts made in Germany, as we see with these chucks. I assume the logo with the R is from the German manufacturer, but I have been unable to determine the name.