Apivar is THE industry wide accepted miticide for effectiveness and ease of application. It is widely available from just about any bee supply house. I personally would not use it while supers that I later intend for honey are present. Better to pull the supers, treat and feed if necessary, and then put the supers back two weeks after you remove the strips. This is consistant with the instructions for use. Use simple latex or nitrile gloves when handling and always wash your hands afterwards. The active ingredient, amitraz, is still found in some flea and tick collars used on pets last time I checked.
Thankfully, the bees are smarter than I am. They are doing well, in spite of my efforts to help them.