Model 6291 photo multiplier
||Printed in green on the base of the tube
||Stamped at the top the tube
||Second number stamped at the top of the tube
overall: 4 3/4 in x 1 1/2 in x 1 1/2 in
The record contains ten 12 pin vacuum tubes type 6291. The tube has a brown plastic base and a mirrored top.