From the Manufacturer
The 856-B wired push button features a polished brass finish and lighted insert. This push button has a portion that must recess into the surface it is mounted to. It requires a 5/8-Inch (or 16mm) diameter hole to be mounted properly. The plate of this push button sits flush on the surface, while the back portion of the push button recesses into the hole.
Heath Zenith 856 Polished Brass Collection, Wired Push Button, Lighted, Polished BrassHeath Zenith is synonymous with quality, integrity and innovation around the globe. They are committed to developing products that enhance their customer's lives through peace of mind, safety and convenience. Heath Zenith has been the leader in innovative and quality products for over 60 years.Heath Zenith 856 Polished Brass Collection, Wired Push Button, Lighted, Polished Brass Features: Polished Brass Finish Lighted Recessed Mount (.625" hole required) 1.25"w x 3.125"h x 1"d 1 Year Warranty