Product Name: Aquarium Undergravel Filter;Fit for: Aquarium, Fish Tank;Material: Plastic Each Size: 140 x 70 x 12mm/5.5" x 2.8" x 0.5"(L*W*T);Total Size: 280 x 140 x 60mm/11" x 5.5" x 2.4"(L*W*T) Tube Size(.): 32 x 2.5cm/ 12.6" x 1"(H*D);Air Line Hose Size: 50.5 x 5mm/2" x 0.2"(L*D) Air Stone Size: 2.5 x 1.4cm/1" x 0.6"(L*D);Main Color: Black, Clear Weight: 420g Precisely made, smoothly buckled, and easily composed. Different sizes could be made up to fit for different fish tanks. Excellent material and easy to clean. Usage: clean tank and rinse thoroughly, connect the bottom plates according to the size of the tank and place it into the tank, buckle stem holder on suitable plate, insert stem holder from top with returnstem and twist to tighten, adjust returnstem according to the height of the tank and lock it with a locking link. Slip a set of exhaust fitting over the returnstem and let air stone touch the plate. Place rinsed gravel over filter plates and fill aquarium with water. Connect air line tubing from to air switch and start pump. Package Contents: 20 x Fish Tank Undergravel Filter 1 x Tube 1 x Air Hose Line w Airstone Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.