The 6CM7 is a dual triode with dis-similiar triodes designed for use a a television frame oscillator and amplifier. The electrically identical 8CM7 has an 8.4 Volt heater and takes 0.45 Amps, both are designed for series heater chain use.
Side view of the amplifier anode. The blackened anode sheets are stitched together and the grid supports are made of copper with heat radiating fins attached.
The low power oscillator triode is on the left with the amplifier triode on the right. The oscillator triode has neither copper grid supports or heat radiating fins.
The thin glass tube envelope is 21 mm in diameter, and excluding the B9A base pins is 57 mm tall.
Reference: Datasheet. Type 6CM7 was first introduced in 1955.