Penn Plax Smallworld Water FilterThe Smallworld Air Filter fits all aquarium shapes and sizes. Contains top quality carbon zeolite for chemical filtration, and is a convenient, disposable filtration unit. This filter includes a bracket measuring 4 1 2"x 1 1 2"x 1" and fits in almost any small aquarium with an easy to replace disposable cartridge filter. Compatible with any air pump air pump sold seperately Filter removes harmful gases, odor and discoloration Disposable, quick and