Most models use light sensors (dusk-to-dawn) that turn the light on in low ambient light and off in daylight, and many also include motion sensors that only activate when it’s dark. Product details document motion detection of up to about 25 ft and typical timeouts around 90 seconds.
Brightness varies by model: small guide lights are listed around 4 lumens, while a brighter plug-in light bar is listed at about 100 lumens. Listed maximum wattage values in product details range roughly from 0.05 W to 1.8 W.
Many guide lights and light bars are slim or designed to occupy only one receptacle so the second outlet remains free. Some cover-plate designs specifically note they leave a second receptacle available for other plugs.
Most are electric LED plug-in lights (product details often list “Battery: No Battery Used”). Outlet-cover or wall-plate lights install by snapping onto an existing outlet or switch plate and require no wiring or batteries; plug-ins simply plug into a receptacle.