This is an immersion circulator - you can use any container you want, this can be attached to the side or hung into the water. So I'll just slide this down into the large pot I currently use to hold 1.5-2 gallons of water. Keeping a constant temp of, say, 155 degrees for an hour was a constant struggle, temp would either keep climbing or drop too much. with this guy I can set up my pot + bag + circulator then take off for an hour.