20th Century Electronics Standard Leak

This device measures 310x50mm overall

This is a Standard Leak. It is basically a glass chamber containing helium that 'leaks' the helium through a membrane at a known rate. It is used for callibrating purposes for example in mass spectrometers.

The markngs on the label are:

Serial no. 147
Leak rate 1.8 x 10^-5 lusecs +/- 20%
Helium filled
3.1.63 (1963)