Observ-O-Scope 5 in 13mm diameter quality lens Adjustable for door thickness from 1 75 in to 2 25 in 33 to 57mm FEATURES The exterior lens is constructed of a scientific glass to prohibit scratching while creating a field of vision exceeding 160 degrees All viewers are furnished with a shutter INSTALLATION Drill a 5 in 13mm hole completely through the door insert the lens portion into the exterior side and the slotted scope portion through the interior side Tighten together with a slotted screwdriver or a coin PACKED Individual poly-bagged - Buy Now or get More Info on Baldwin Hardware - Click Here To Order