While I have been using condoms for years to cover the transmitter packs, our local civic group has come up with a better and cheaper solution... The cut the neck off of balloons and stretch them over the cases. They are just as water proof, are tougher to rip and are a LOT cheaper!! So far we have only had to replace one after two nights of rehearsal. On that one, the actor snagged the mic and I had to re-solder the connections. I hate soldering those tiny little wires(Countryman mics).