As I stated in my original post, I use Harbor Freight 9 volt rechargeable batteries. They do fit in the housing very tight, but I suspect this is so they will make good contact all the time since they don't have a snap-on connector. Instead, they are pressed tightly against the contacts. The Mikes get a lot of use during a show and I'm well pleased with the Mikes (VocoPro VHF-3300) and the battery performances.
KOD
