These are typical 1/6 keg or ECO kegs and I bet they are Chinese. One of the local brewerys - Straight To Ale - just brought in pallets of these direct from China and they are very happy with them.
I've acquired some of these and they are OK. Just slightly bigger than a Ball Lock Keg. Not sure what to do with them? I wish they were like 5.75 gallons. Would have made an awesome fermenter.
Check probrewer, there are a few vendors in the for sale section selling them cheaper.