The Wireless Plug-In Doorbell Kit includes 1 chime and 1 push button with lithium coin battery included. Kit components come pre-synced, making installation quick and easy with just a flat-head screwdriver. The chime can be mounted anywhere in your home within transmission range of the push button. Up to 3 additional Home Depot non-branded wireless push buttons (sold separately) may be installed and synced at other entrance points as well. However, please note: Home Depot non-branded wireless components are NOT compatible with competing brands.