The Telefunken RL12P35 is a German transmitting pentode dating from the WWII era designed for HF and low VHF use. The Type indicates the 12 Volt heater and the anode dissipation.
One of the top caps is clearly marked A for anode and the second top cap is taken to the suppressor grid. The anode dissipation is 35 Watts.
The base is of a bayonet locking type with five small base pins. The skirt hides the electrodes and is indirectly heated with a circular cathode tube.
The anode side supports are ceramic rods and at the lower end is a screen shielding the pinch.
The grid wires can be seen above the base screen. On the glass is the BAL716 identification to show it was made to the German Luftwaffe standard and inspected at that particular office. The lettering above is RLM Eigentum, equating to property of the Air Ministry.
The two screw top caps with the letters A and B. The centre screen is made of fine mesh.
The copper tape connects the anode to the top cap A.