I can't find a suitable airbrick/ventilation grill

[smp50]

I'm trying to replace a typcal white louvred vent cover, similar to this:

But other styles will do. I need one that's 10" x 7", which seems to be very unusual. 9" x 6" are everywhere, but unfortunately that won't fit. The plastic channel in the wall needs to receive the screws so the few 10" x 7" vents I've found don't even fit. Even ones of the same brand (Stadium) today have a different surface layout and the screw holes don't align.

Am I probably stuck? The worst case scenario is having to stick the vent to the wall with sealant, which is not ideal but it would have to do.

Can anyone suggest some good vendors that sell a very wide range of different vents? Or, in reality, do people usually have to just stick them on due to this compatibility issue?

Thanks,

 

[Blagard]

Have you considered a 9x 6 plaster vent that you can stick on? - use something like plaster cove adhesive. But to be honest there is nothing wrong with sticking the plastic one on with silicone, it just might not be as secure as the one below.

http://www.travisperkins.co.uk/p/plaster-louvre-fly-screen-vent-9-x-6/810508/2893350

The plaster one can be painted to blend in as well

Bigger plastic:
http://www.travisperkins.co.uk/p/4trade-louvre-vent-fixed-flyscreen-white-241-x-165mm/966907/2893350