This style of Safety Valve Kit Millennium has been discontinued by Pavoni and replaced by the new version. Please see this link for options, including the Chrome Valve, Brass Valve and Complete Assembly -- parts 1515069, 1515069, and 1523025 respectively.
NOTE: NEWER version, the shaft is pear shaped without the black o-ring.
Also called “pressure release valve.”
Fits: Europiccola and Professionale models built in 2000 or later, called Millennium models, as well as late 1990s PRE-Millennium models with a red rocker switch and green light. Does NOT fit PRE-Millennium models with an ON/OFF switch or PRE-Millennium models with the double switch.
For a more detailed explanation, please see this PDF.
To watch Stefano's How-To video on You Tube showing how to remove the valve body and replace the valve, see thislink.