Vacuum tube type 6SN7
The object is from the Whirlwind collection. Information on a piece of cardboard found in the box reads "Bus Driver Arithmetic Rack S/N4" and "5881 in 6SN7 slots." The tube has 8 pins.
||Stamped on the top of the object
overall: 3 in x 1 1/4 in x 1 1/4 in
Gift of the Digital Equipment Corporation