When you clean your DSLR sensor using the LensPen SensorKlear system, you can see what you are cleaning while you clean, a feature no other sensor cleaner can offer. It makes sensor cleaning simple, fast, easy – and more effective. The SensorKlear Loupe is easy to use; just remove the camera lens, place the Loupe on the aperture ring, turn on the light and inspect the sensor. If it’s clean, there’s nothing left to do but put the lens back on. If the sensor is not clean use the Hurricane Blower to remove the dry dust. Inspect the sensor again.If sticky dust remains on the sensor, insert the angled tip of the SensorKlear II pen through the access window on the side of the Loupe to safely and easily target and remove the sticky dust. Only the LensPen SensorKlear Loupe has the access window to allow the user to see and clean at the same time.