This Gre cartridge replaces the paper element in your cartridge filter. Instead of pleated paper it holds loose polyethylene fibre balls, kept together by a net so they do not drift around the housing.
Gre lists AR125, AR124, AR121, AR118 and CFS20 as matching units, plus the AR11806 for inflatable pools. It is the type A size, so it also fits compatible filters of that same type.
Changing it goes as it always does: shut off the pump, open the lid, take out the old element or the old Aqualoon, put this one in. The manufacturer states that the net can be washed out and used again - that is the difference with a paper element, which you throw away in time.
Worth laying in a spare in the garden shed, so you are not caught short halfway through the season.
