Specially designed for increasing oxygen levels. Easy and convenient to use. Prevent stopping up,good for oxygen pump use. Creates water currents and dazzling underwater scenes. An important tools to keep aquatic fish for respiration process. Specification: Material: Copper 4mm Length: approx.4cm or 1.57inch,Outer diameter:approx.4mm or 0.16inch 8mm Length: approx.5cm or 1.97inch,Outer diameter:approx.8mm or 0.31inch Package Includes: 5x 4mm or 2x 8mm Air Stone Aerator 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 of the pictures and the actual item. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.