Just came across these on ebay after ordering one for £16. Seems like a good price to me. Benefits of the activated carbon filter, as opposed to a standard one, are it's supposed to remove smells and catch various dangerous gasses (or something like that)

Order your air filter put BRISK25 as a code they are sponsors on here for 25% off

Eh? This is an "outlet" version of ECP so prices are cheaper anyway - so these codes do not apply.