The AZ41 is a full wave rectifier. The heater at 4.0 Volts looks back to the pre-war UK standard and the all glass miniature envelope looks to the world of post war miniature valves.
The AZ41 must have a minimum of 200 Ohms series resistance to limit the maximum current. The maximum reservoir capacitor must be no more than 50μF.
The side view shows the locating pip at the lower right hand corner.
The B8A base pins are equi-spaced and the locating pip is essential for correct orientation.
The thin glass tube envelope is 20 mm in diameter, and excluding the B8A base pins is 68 mm tall. The wider section at the base is 21.5 mm in diameter.
References: Data-sheet, 3002 & 1040. Type AZ41 was first introduced in 1947. See also1947 adverts.