They are 50 Liter and 60 Liter stainless pots fitted as a double boiler with small wire racks between them. Started doing 12 and 25 litre batched in smaller pots, but they keep on growing our ambitions grow to dol arger Cheeses. I think this may be the limit as any bigger will not balance on my cooker.
These pots are used by street hawker in Singapore to cook large batches of whatever they sell at their hawker stand. Hence, quite cheap to buy (50 liter was about $80).