Nakamichi CM-300 Microphone battery adapter insert

The Nakamichi CM-300 microphones are an old condenser microphone that works extremely well with acoustic instruments and are pretty inexpensive. But they use a 9V battery which is hard to find and doesn't last very long. I found a pair of batteries - a 3v and a 6v that stacked up fit in the microphone body - except they're skinnier and flop around a bit. This adapter keeps the batteries in the middle of the body. The batteries are a CR2 (readily available) and an A544 (hard to find in stores