For me, this makes a lot of sense rather than having to rely on gas heating or lugging a battery to all of my hives. I’ve wanted one for a while, but asked for contributions to the cost for my birthday a couple of months back and finally ordered it over the weekend.
It’s the Instantvap compact oxalic acid sublimator. Easy-peasy varroa treatment. All my hives now have a rim on the floor through which I can drill a 7mm hole and insert the brass nozzle without even opening the hive. I’ve read that a golf tee works nicely to plug the hole when it isn’t in use so the bees don’t propolise it up.