Ours is a Morphy Richards 'Compact Steam' Katog. Has a 2.2KW element to heat 1 litre of water and a 2 metre insulated hose with a variety of fittings- although we only ever use the fine jet. It may be obsolete now though?
You will have to do it more than once because a small percentage of red mite will remain on the hens and will get off them at night and re-infest the coop. We deal with that by treating the perch ends with creosote (only the ends), removing it every morning and killing all the mite trapped on it by the creosote. After a week or so there will be none, but still check as they can pick them back up from their soil bath.