Hagen Fluval U4 Underwater Filter.

Adjustable 3-way flow control feature lets you position the water flow output to meet your specific needs, Top Output setting provides maximum circulation and oxygenation, Integrated Spray Bar setting provides a gentle, even flow for planted aquariums, Bottom Output setting is for deep water agitation, Convenient flip-top lid allows quick and easy access to the filter cartridge for maintenance or replacement, Can also be placed horizontally in shallow water tanks or to create decorative features such as waterfalls, Can be installed vertically against the aquarium wall to create currents or customised flow patterns.