A bit confusing - when I click on the link I seem to arrive at a different place in the Trend website each time - I'm guessing you are talking about the Airshield Pro Respirator rather than a router to be used as a die grinder (which is, I think, what Gordon assumed)?
Sorry can't help with your question though!
Edit: Huh - just tried the original link again and it went straight to the respirator - weird.
Iv'e got one and use it mostly when woodworking.
It seems to work just as well for plasma cutting and grinding.
No crunchy black snot and the filters look very grubby which implies that they work.
At 20 quid a pair I wash mine and reuse them.
A bit heavy on the head but not too bad.
I would say pricey but worth the effort.