The MS4B glass version was issued before the catkin version MS4B that was issued in 1933/4. The original MS4 dates to 1929.
The missing top cap connector was almost certainly of the black screw-on type.
It is a tetrode from the early mains valve era with its 4 Volt heater and it offered 'maximum amplification', whereas the earlier MS4 was a general purpose screened grid valve. The screened tetrodes and pentodes were employed for RF and IF amplification.
The balloon envelope is 43 mm in diameter and, excluding the B5 base pins, is 110 mm tall.
References: Datasheet & 1040. Type MS4B was first introduced in 1931.
Absolute Maximum Operating Conditions¶
Updated March 21, 2014. shape:balloon construction:pinch type:tetrode age:1930.1940 base:b5 heater:4.0v pins:4 pin:1.g2 pin:2.g1 pin:3.h pin:4.h pin:5.k pin:tc.a