Aquarium Fish Tank Plastic Undergravel Filter Black 12 Pcs with Connector TubeCategory: Undergravel Filter SystemPrecisely made, smoothly buckled, and easily composed. Different sizes could be made up to fit for different fish tanks.This filter board is constructed of 3 layers 12 pieces small filter board.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.?For CALIFORNIA residents only: WARNING: This product contains chemicals including DEHP, which is known to the State of California to cause cancer and birth defects or other reproductive harm.Please note that by posting this Proposition 65 warning, we are notifying you that one or more of the Proposition 65 listed chemicals may be present in a product. With Unique Bargains' products, the exposure to these chemicals may be of no significant risk to you, but out of caution, we have elected to place this warning on our site to make sure our customers are informed.You can find more infomation at http://www.oehha.ca.gov/proposition-65/about-proposition-65.