This jacket is designed to insulate your 27 Liter FermZilla during the colder months to keep your fermentation at the optimum temperature. It can also be used with a heating belt/wrap to warm up the wort if the heat from the fermentation isn't enough. It is large enough to freeze a couple of plastic soda bottles full of water and put them inside the unit for cooling. Also completely blocks any light/UV to prevent light stuck beer.
This also fits our V44, 60 Liter All Rounder Fermenter.