Can anyone tell me what this fixed sink plug is called?

[Trevorleach]

Used strong drain cleaner which turned my chrome a dull gold so now need a new one, ******** if I can find one as I have no idea what it is called, literally going around in circles on one site after another.
The chrome bit is fixed so the sink never fills and so cannot overflow, underside has M6 studding and you basically remove the trap to adjust the height of the chrome disc widget.
So what I would like to know is what do I search for?

 

[angellonewolf]

free running basin waste?

 

[Pete.]

Do you mean the sink waste outlet or the overflow?

https://www.screwfix.com/p/flomasta-unslotted-free-flowing-grated-basin-waste-chrome-plated-brass-32mm/579JN?gclsrc=aw.ds&gad_source=1&gad_campaignid=19822796606

 

[Trevorleach]

free running basin waste?

First hit on ebay 15 quid, thank you

 

[angellonewolf]

im sure screwfix would one as above and you can collect tommorw and possably better quality

 

[angellonewolf]

https://www.screwfix.com/p/highlife-bathrooms-unslotted-free-flowing-basin-waste-chrome-65mm/397RW?tc=XT8&gclsrc=aw.ds&gad_source=1&gad_campaignid=19822796606&gclid=Cj0KCQiApfjKBhC0ARIsAMiR_IvvGROjeVwLh_BPF13HQe28zoErHO4FyevUt5tubsrYWgPMRRB2VuwaAoIzEALw_wcB