This is a General Electric 6072A especially selected for the AKG C12 tube microphone. RAM is the current supplier of these tubes to AKG. The tubes are tested to AKG's specifications. 6072A - For AKG C12 Tube Microphone - Standard Quality $70.00 6072A - For AKG C12 Tube Microphone - Better Quality $150.00 6072A - For AKG C12 Tube Microphone - Best Quality $250.00 Need assistance? Email info@tubeaudiostore.com or call 805-687-2236. Photography by VisionQuest Photography