SURFACE MOUNT: this doorbell push button can be easily installed on almost any wall or flat surface area SPECS: total length: 2.89"; distance between screw holes: 2.09" MAXIMUM VOLTAGE: when installing and using this lighted push button doorbell, do not exceed 16 volts LIGHTED: the built in light makes finding the doorbell button a breeze, especially in darker settings WARRANTY: this push button doorbell is guaranteed with a 1-year limited manufacturer's warranty