Looks fun 
I’ve something like that… Its a stone attached to an old racking cane with a valve… I guess it does work, but you have to swizzle it around for a while… You send me your address via secret email, and Ill send that to you… Sneezles61
Seen them, never used one. You could go much cheaper by adding a stone/tubing to the gas in post. Of course I still think the CO2 will need to hydrate.
Other option, blow the CO2 in the liquid post… if you want… Sneezles61
