Emergency lights
Emergency lights (sometimes called safety lights, or back-up lights) are small and light enough to leave on your bike, in your desk drawers or in your bag while commuting, ready to be called into action should your main lights fail.
Invariably lit by a single, low-powered LED, emergency lights will put out somewhere in the region of 15 to 25 Lumens; not a huge amount of light but enough to get you home. We’d also recommend having small blinker lights permanently attached to your bike to use on overcast winter rides when, even in the middle of the day, visibility can still be poor.
Emergency lights are normally attached to the bike using a silicone band, like the Knog Blinder 1, Lezyne Femto and Revolution Flash lights. The Lezyne Zecto Drive Pro is perhaps the ultimate emergency light as it can be used as a front (white LEDs) or rear (red) light.