Works great in a Gaggia Classic and Breville Double Boiler,
This review is from: Espresso Supply 58-Milimeter Backflush Insert, Metal (Kitchen)
Very handy accessory for a Gaggia Classic and a Breville Double Boiler. Fits the portafilter for each perfectly -- not too loose nor too snug. Makes it a snap to backflush the machine.
I use this for when I'm backflushing the machine with a cleaner, which I do every couple of weeks. For clean water backflushing (which I do every couple of days) I use a rubber insert (comes with the Breville; I use this one for the Gaggia Backflush Insert, 58mm, rubber) since that's easier to pop into the portafilter right after dumping out the puck. The rubber insert is faster to put in, but messier than using the metal insert.