Simply the safest and best way to blow clean, dust-free air to clean lenses, cameras, filters, keyboards or any of the other places where dust resides! Medium size is 170mm long and 55mm diameter for a large volume of air. Made from the best quality silicon rubber for long life and instant rebound to deliver almost a continuous stream of clean air! Each rocket has a long thin tip with a uniquely designed opening to eliminate whistling. A one-way valve on the bottom brings in clean air and does not re-distribute the dust!