Re Filters,
I used mine for about half an hour and the Filter blocked.
As far as I can tell Filter will then need to be cleaned and washed as mine really was thick with dust.
Therfore Spares are required.
I think they are £6.50 from Hometek.
This was just my personal test report
Once Filter was cleaned and dried full pwer was restored, but for time being have reverted to Henry and just use Hunter for Final quick going over.