The Serfas Thunderbolt features a incredibly bright 50 lumen LED strip, you really don't need anything more for a tail light, brighter lights can be annoying to drivers.

The Thunderbolt can be fastened almost anywhere on the rear of your bike, the seatpost, seat stays or on most rear racks with an adapter.

With a flash output up to 6X as visible as typical rear lights, the run time is up to 19.5 hours.

High solid and low solid modes are available as well with 1.5 and 5.5 hours of run time respectively.

Includes a seatpost mount and USB recharging cable.

Backed by Serfas' outstanding lifetime warranty.