Built-in siren. Stick Up Cam Battery comes with a Quick-Release Battery Pack, and you can also use the Indoor/Outdoor Power Adapter (sold separately) to plug it into standard UK/European power sockets. Works with Alexa voice commands and IFTTT. Easy to install. Sharp 1080p video. Ring's latest indoor/outdoor Stick Up Cam is available in plug-in and battery versions (I tested the battery model), as well as a $149 model bundled with a solar panel accessory. No hub required. With the battery pack inserted, Stick Up Cam Plug-In will be powered by the adapter and will use the battery as backup. The main difference between Stick Up Cam Battery, Stick Up Cam Plug-In, Stick Up Cam Solar and Stick Up Cam Elite is how they receive power. Stick Up Cam Battery is powered by the Quick-Release Battery Pack. Completely wire-free. Motion detection.