The Brimar R2 full wave rectifier is constructed as twin sections held between mica sheet and sitting on top of a pinch.
The Brimar Logo on the base.
The anodes have a central cylindrical cavity for the cathode tube and the blackened anode plates are perforated..
The classic envelope is 44 mm in diameter, and excluding the B4 base pins is 102 mm tall.
References: Data-sheet & 1043. Type R2 was first introduced in 1933.