The Oasis Case Humidifiers lets you see when it's ready for refill</br>Secure but detachable magnets and clip</br>Refilling Syringe for greater control when adding distilled water</br>It works with any string instrument case</br>Unless the refill cap is opened?? outside air cannot get in to replace the evaporated water</br></br>Product Description</br></br>OH-6 Case Humidifier</br><br/>http://www.amazon.com/gp/product/B0010XSZ3A