Product Description This viewer features a threaded diecast housing and solid brass constructed end caps. It fits on 1-1/2 in. to 2-1/8 in. thick wood or metal doors. It has a bore size of 1 in. and also features glass lenses. From the Manufacturer This viewer features a threaded diecast housing and solid brass constructed end caps. It fits on 1-1/2 in. to 2-1/8 in. thick wood or metal doors. It has a bore size of 1 in. and also features glass lenses.