EcoSystem Hang On 40 Marine filtration system for 10 through 40 gallon aquariums. Includes 9 watt power compact light unit with return pump, return nozzle, sponge, preskimmer box and U-tube. 18 inch long by 4 inch wide by 9 inch high acrylic filter includes 3.5 lbs. Miracle Mud. Designed for use without a protein skimmer.