The CV1133 is a high voltage high vacuum rectifier. The pre CV name was the VU133 and this exhibit carries both names. This shows that it was made before 1941 and the CV Type was overprinted.
High anode voltages demand the additional insulation of ceramic.
The pinch. The filament is folded and passes through the cathode tube four times.
The classic envelope is 50 mm in diameter, and excluding the B4 base pins is 121 mm tall.
