In- Aquarium Glass Poppy Inflow Outflow Pipe 1 Set For Planted Fish Tank 12/16mm 16/22mm Canister Filter Surface Skimmer Filter Tube Sliding Lily Pipe Outflow above the waterline allows it to also serve as an aerator which eliminates oily surface film. Also you can prevent deficiency of o during the night. Inflow Pipe Glass Inflows are designed to transport the water from the aquarium to the external canister filter. This simple design glass pipe has suction slits. For use with a frame-less aquarium tank. Outflow Pipe This outflow pipe bringing clean water from the filter backto aquarium. Moderate water circulation evenly within the aquarium is essential to maintain the water quality and prevent algae appearance. Use with canister filter. 10mm fits 9/12mm (3/8 ID) hose. Fit for fish tank below 30cm 13mm fits 12/16mm (1/2 ID) hose. Fit for fish tank 30-90cm 17mm fits 16/22mm (3/4 ID) hose. Fit for fish tank 100-150cm Notice: Due to different production batches, there would be some difference on packing or other improvement, it won't affact the funcation, please enquiry us first if you are mind of this issue. The measurement may have 2-3cm error as the difference measuring and difference production batches, hope you can understand, thanks! The colors may have different as the difference display,please understand. Normally we will proceed your order in 3 days and send you the goods with