This is a Sylvania developmental power pentode in a glass envelope with an eight-pin loctal base. This is a spare tube for Bus Driver Flip-Flop Storage Rack S/N 6.
Date
1925 ca.
Manufacturer
Sylvania
Place Manufactured
U. S.
Identifying Numbers
Model number
SR1407
Printed in silver on top of the glass envelope.
Other number
MS V6-2
Handwritten vertically in silver ink on the glass envelope.
Other number
XAD4848
Stamped in green ink near the bottom of the glass envelope.
