Thank you for the replies - especially given that there's not much information in US pages.
The montalcino report is a nice write up and I got the translation "hydraulic bung" from there. I had spent an hour searching something with that or similar names in the US without success.
You are right, Pumpkinman, it is like a 3 piece airlock, just bigger and of a different shape. I inserted a 3-piece last night and filled it with wine. This morning the wine was gone. So a real "colmatore" would do a better job.
I moved to the US from Italy several years ago and recently upgraded from carboys and demijohns to a barrel or two. And then realized that a "hydraulic bung," or whatever it might be called in the US, would be really helpful to monitor for and prevent certain type of spoilage.
Most of the wineries I visited in Italy use this device for regular (59-60 gal) and bigger (250 +) barrels and it is available in online stores as well. Problem is that I found only one store that would ship to the US but they want $60 shipment for something that's less than half a pound heavy.
I also asked the owners of two local wineries (Virgina) and they've never seen it either.
I guess I'll order from Italy and drink a slightly more expensive but healthier San Giovese.
Thank you again!