The BrewSnug25? is a neoprene fitted jacket with built in temperature controller and heating band designed specifically for the BrewKeg25?. A thermostat probe attaches directly to the sediment bottle to read the temperature where it matters most. As a stand alone heating device, the BrewSnug25? allows brewers to maintain a minimum brewing temperature for fermentation without the need to tie up a beer serving fridge for the same purpose when you would prefer to be drinking from the fridge! The BrewSnug25? has been tested to an ambient surrounding temperature of 4 degrees Celsius, at which it is able to maintain a 20 degree Celsius brewing temperature for the BrewKeg25? It is important to note that the Brewsnug25? will only work on the new style of Brewkeg25?. The older style Brewkeg25? is lightly taller and won?t fit inside the Brewsbug25??