23 Inch by 11 Inch Under-Gravel Aquarium Filter ? Undergravel filters work by the bubbles from the aquarium airpump pushing water up the uplift tube or a power head pulling water up forcing water through the gravel to replace it so filtering the aquarium water. Will fit a aquarium up to 24 Inches long and 11 Inches wide. Airpump required (not supplied) ? 23" by 11" Undergravel Filter ? Comes with two uplifts ? Has plugs to be able to use just one uplift ? Strong Plastic construction ? Comes with airstones ? Airpump Required (not included) We Sell Many Aquarium Pond Products, Check out our Store Terms and Conditions. We use PayPal for taking payment, if you wish to purchase via other methods please email us for customer service. Sales Tax will be added to all shipments to New Jersey. We always try to combine purchases, please contact us directly for a personal service. You will be notified on the day that your goods have been dispatched via e-mail with tracking which is used on all purchases. Please note that if there are any problems, contact us first via e-mail giving full details of any problem along with your user ID. We use USPS and UPS as our chosen carriers shipments to Hawaii, Alaska Puerto Rico may incur surcharges, contact will be made to advise before shipment at which point the order can be cancelled if desired. Orders placed on Saturday/Sunday Public Holidays will be processed next working day. We pride ourselves on excellent feedback, if any part of the buying experience is not to your satisfaction, please contact us to rectify before leaving feedback. By committing to buy you are agreeing to the Terms Conditions stated above.