A mark 2 9Barista safety valve.
It is compatible with all 9Barista machines.
The mark 2 valve has a pressure release button that is designed to equalise the partial vacuum that exists in the boiler after brewing. Pressing the button will make unscrewing the boiler after brewing much easier.
All 9Barista machines sold after February 2020 came with one of these mark 2 valves as standard.
Warning: The button should only be pressed once the 9Barista has cooled down. The button may be burning hot during the operation of the machine and may release burning steam if pressed before the whole machine has cooled down.
This valve comes with a thermal safety ring as standard and is ready to fit to any 9Barista machine. You should be able to unscrew the existing valve by hand. You only need to tighten the valve "hand tight". But if you need help, a 13mm spanner is all you need.