Even though most new houses these days are pre-wired for smoke detectors (devices we'd hope would also have battery
backups), there are countless dwellings with battery-only devices that probably go unchecked, let alone all those
houses out there with poorly positioned working alarms. But Dupont's Self-Charging Smoke Alarm kills two birds with one
stone by integrating a smoke detector with rechargeable battery with a pass-through light bulb socket, so you can stick
one in every room if you so choose. Apparently you can even test the thing without busting out the ladder — just flip
the switch twice (or flip three times to silence the alarm and reset the device).