The Supernova E-Bike E3 V521s front light is based on Supernova's V6s housing. However, it offers the advantage of completely revised electronics that accept voltages up to 21 volts. Its remarkable "Softstart" function enables it to be used with systems sensitive to starting currents, for longer life and greater lighting consistency. The Supernova E-Bike E3 V521s front light features the following characteristics Supply voltage: 5 -21 V 205 lm Lens type: Terraflux 2 Softstart for compatibility with BROSE, Alber, Bosch, etc. Optimized for permanent daytime running light Cable length to battery 1080 mm No rear light cable, no switch Aluminum bracket for handlebar mounting 31.8 mm next to stem