The 6B5 (equivalent to the 6N6G) is a double triode. One triode is a voltage amplifier and the second, directly coupled to the first, is an output audio triode. The output triode needs to work to a 7,000 Ω load and can produce 4.0 Watts of output. The grid bias is internally generated.
The Sylvania logo on the base and power triode anode.
The power triode on the left with the triangular anode plate.
The top mica: the power triode has copper grid supports.
The power triode anode with the distinctive anode shape.
The classic envelope is 45 mm in diameter, and excluding the IO base pins is 101 mm tall.
References: Data-sheet, Data, Data & 1043. Type 6B5 was first introduced in 1937. See also1937 adverts.
