"Overall Outside Diameter: 1 7/16” (36.5 mm) : This is the outside diameter of the clock face Mounting Inside Diameter: 1.28” (32.5mm) : This is the insert diameter of the opening that the clock fits in. With addition of the ring gasket (included) this increases to 1.36"" (35 mm) Mounting Depth: 1/4"" (6.35mm) Miniature Clock Face Insert ************************************************************* Fits In Many Types of Small Glass & Crystal Clocks. Quartz Movement PC21 Quartz Movement with a long life battery. Please confirm measurements before ordering."