The CV2329 (commercially the 4004B) is a current stabiliser or Barretter. This ballast device will hold the current flowing through it at 0.25 Amps for a voltage between 3.0 to 9.0 Volts.
The active element is a coiled iron wire wound on what looks to be a thin glass filament.
The STC logo and the commercial Type designation.
The wide glass tube envelope is 28 mm in diameter, and excluding the ES base is 98 mm tall.
Reference: Data-sheet. Type CV2329 was first introduced in 1954. See also1954 adverts.
