Precision production,smoothly buckled,easy to assemble and connect. Different sizes of any combination , all kinds of fish tank applicable. Plastic material and easy to clean. If driven by a water pump, connect the water pump to the special pipe above the bottom filter.If driven by air pump, connect the air pump outlet to the sand head on the bottom filter. Specification: Material:Plastic Size(LxWxH): Approx. 28x14x1cm/11x5.5x0.4inch RS-24P Tube Length: Approx. 32cm/12.6inch RS-28P Tube Length: Approx. 33cm/13inch RS-32P Tube Length: Approx. 31.5cm/12.4inch Package Includes: 7 Pieces Boards+2 Pieces Tubes Note: Since the size above is measured by hand, the size of the actual item could be slightly different from the size above. Due to the lighting effects, monitor settings, etc. There could be some slight difference in the color tone of the pictures and the actual item.