This handsome medium size hygrometer features a real glass lens face and beautiful polished gold frame. Dependable & accurate. Technical adjustments can be made at the rear of the hygrometer for easy calibrating. Includes double faced velcro adhesive to secure to the interior of any humidor. Features a color-coded easy to read face that displays relative humidity (RH) . This model can be inset into a pre-made hole or can be mounted anywhere with the Velcro that is provided. Front Diameter- 1-3/4" ; Back Diameter- 1-9/16"