The 150A is a current stabiliser or Barretter. The envelope says that it is for regulating at 0.2 Amp.
This exhibit has been measured at 130Ω cold.
This Barretter is on the B4 base, our other 150A Barretter is fitted with the Ct8 base cap that was used widely in Continental Europe but far less so in the UK.
The wide glass tube envelope is 38 mm in diameter, and excluding the base pins is 116 mm tall.
Updated September 28, 2016.