Busch & Müller Top Fire helmet lights comprise four flashing LEDs attached by cables to a clip-on switch that houses a CR2032 battery. They’re not a substitute for conventional lights but as an extra visibility aid, whether commuting or time trialling, they’re great.
You stick the LEDs into your helmet vents with the adhesive pads provided and fasten the coin-sized switch to a helmet strap – behind one ear, perhaps.
You need to take more care when putting on your helmet, but if an LED comes loose it’s easy to stick back in. We found that the LEDs fitted well in the vents of a Bell Meteor Aero helmet (fastening the switch to the internal cradle) as well as in more conventional helmets. You could probably fix them in other places too such as under a saddle or on the back of a recumbent seat.
Run time is around 100 hours, and they weigh 18g, including the battery.