Phat filters come packed inside a plastic bag to keep your charcoal fresh. Once you open your Phat filter box, remove this bag and wipe down any extraneous charcoal dust that may have accumulated during transport.
Inside the filter you will find another plastic bag containing your white pre-filter. This is a Dacron cover. Remove this pre-filter and slide it over the filter canister until it covers the entire perforated metal portion.
Also in the bag will be two elastic bands. Attach one band near the top of the filter and one near the bottom of the filter. These bands help secure the pre-filter.