TonoClear Disposable Applanation Prisms (100 per Box) Sterilization Tray The LensChek Digital Lensometers utilize VOVG4 The LensChek Digital Lensometers utilize a Green Measurement Light which gives a more accurate measurement without the need for Abbe value compensation the device automatically enters sleep mode after 30 seconds of inactivity and powers off after 4 minutes without use The Tonoclear is designed to be less affected by the intensity of light and internal reflections which enables the user to gain a clear image of the miers to improve both accuracy and speed of measurements Sterility – Prisms are single use and come Ethilene Oxide sterilized