Help identifying part

[Flash72Uk]

I have a leaking "flexi valve", at least that's what's printed on it.
Please see attached pic, it's the thing on the top with the red "cap" on it. Not much luck in searching for a new one online and would be grateful if anyone could point me in the right direction. Thanks.

 

[danielp]

this is an automatic air vent

Honeywell EA122 Automatic Air Vent With Adapter EA122 Plumbing Heating And Drainage Heating Parts And Spares

 

[Flash72Uk]

this is an automatic air vent

Honeywell EA122 Automatic Air Vent With Adapter EA122 Plumbing Heating And Drainage Heating Parts And Spares

B****y marvellous - thank you Daniel.