Fluval U4 Underwater Filter 1000LPHPRODUCT SUMMARY Provides complete and efficient 3 stage filtration For fresh, marine and reptile environments Adjustable 3 way flow control feature lets you position the water flow output 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 for maintenance Can