You put the tablet on the shower floor and it releases eucalyptus, menthol, and camphor vapors. James got a box of them and we have each used a couple of them. If you do what the directions say, they dissolve pretty quickly. I found that if you put the tablet at the end of the tub/shower and only direct the water onto it now and then, it lasts a lot longer. I use it when I am finished with the main part of my shower (shampooing, etc.). It's kind of relaxing!