Pro Optics Clip On Moisture Chamber- Fits Left Eye -- Size Medium - White in Color Ideal for dry - eye conditions Clear vinyl shield with soft sponge edging that gently hugs facial contours. Instructions: The clip-on Moisture Chamber sits behind the eyeglasses so that the foam rests against ones face when eyeglasses are worn. The bottom rim of the frame sits in the bottom hook and the clip is gently slid over the top of the eyeglass frame. To remove gently slide the top clip up over top rim and pull bottom rim of frame up out of the bottom hook.