Sheaths are designed to be used for Intra-Oral images only (using a camera sheath outside of the mouth will result in a fogged image). When applying the sheath, slide the handpiece under the white flap, with the lens facing down. Push the handpiece in until the end of the sheath is taught. Peel away the top blue layer and the bottom paper layer. Using the paper layer press down lightly on the lens for a few seconds to seal the sheath to the lens (the paper will keep oils on your fingers from transferring to the sheath). Please see the photos above to determine which sheath part number is appropriate for your model camera.