It looks similar to ProPex, where a Pex expansion ring is expanded to fit over the end of the pipe and fitting and allowed to shrink. In the Axis system the tubing itself is expanded and then a copper, brass or stainless steel sleeve is crimped over the connection.
It looks to be a very robust connection, but may be overkill. Perhaps that's why I've never seen it used around here.
"The physician can bury his mistakes, but the architect can only advise his clients to plant vines." -- Frank Lloyd Wright