Intex "B" Metal Frame Above Ground Pool Cartridge.
10 inch long, 6 inch wide. Intex filter cartridge 18ft/24ft and Ellipse. These filter cartridges will fit 18ft, 24ft,Frame, Easy set and Ellipse pools.

These Cartridge filters fit Intex pumps that come with the larger Intex  Easy Set & Metal Frame Pools such as with the 24' Metal frame Pool.

Intex recommends that you change your filters every two weeks, in practice & especially during the summer when pool use is normally higher, you may find that your pump runs more efficiently.