Printed in brown ink on top of the glass envelope.
overall: 3 1/8 in x 1 1/4 in x 1 1/4 in
There are 13 tubes covered by this record. This is a pentode vacuum tube with a loctal base. Pin 5 is missing by design. This is a spare tube for Bus Driver-Arithmetic Rack S/N 10. None of the tubes have additional legible markings on their envelopes.