Where to buy generic HEPA filter?

[brownie]

Hello,

I have a Cygnus air purifier, and I am not sure where to buy a HEPA filter that can fit in it. It seems as though I may need a generic filter as I can't find one made by Cygnus specifically.

Any hints as to where I can find an array of HEPA filters in HK (preferably on HK Island!)
Thanks!

[PDLM]

Fortress sells at least three models (two by Sharp, one by Philips) but they seem to be equipment specific rather than generic. But if you're really stuck I guess you could have a look at those to see if any of them fit.