Kloud City Pack of 2 Blue 7'' Long Aquarium Fish Tank Tube Shaped Air Stones with Suction Cups Sucker Creates a dramatic mist of healthful bubbles. Package include 2 Pieces 7'' fish tank tube shaped air stones. They can be connected together. Super porous , non-clogging Additional bubble tubes can be joined with the enclosed connector, and can be cut with a razor blade to divide or shorten. To complete assemblu, replace end plug and air intake elbow. To remove algae accumulation, clean with a soft bristle brush. In hard water areas , mineral deposits may clog any air stoe. the stones, however is the only aeration product which can be easily regenerated. Simply use a pin or needle to puncture with as many small holes as needed. The tough material not only resists clogging, but will aslo stand up under repeated reconditioning.