Why do they insulate these kegs with rubber?
Does any one know if this keg is stainless steel? Or is it aluminum?
If this keg is aluminum, is there any reason not to ferment in aluminum. I'm fermenting a Belgian golden ale that will be transfered into a 10gal oak barrel for aging and souring.

edit: this beer has been fermenting for 5 days in this keg. If this keg is made of aluminum can I still drink this beer?