It is being sold for £50 via a dedicated website - fosterssuperchilledkeg.co.uk. Orders can be submitted through the website, and collected from points of sale across the UK.
Makro cash and carry branches in Charlton, Croydon, Edinburgh, Enfield, Manchester, North Acton and Rayleigh
are listed as pick-up points for
Zeolite, a crystalline mineral, is used within the keg's casing as a catalyst to chill the lager to 3°C .
Off-trade sales boss Mark Gerken said: "We will soon be able to review the outcome of the trial, which is currently being held in selected wholesale outlets across the UK, in order to determine our future plans for the product."
S&N withdrew a previous Foster's keg product - CoolKeg - in 2004.
Both Heineken and Carlsberg have launched keg products this year.
S&N's category plan - page 24.