First of the part looks damn good on the bike, not the most important factor, but not to neglect! The most important is probably the luminosity and therefore visibility. Again, I have to say, excellent. With the spotlight to be seen with certainty even within 100m, probably loose more. The opening angle is completely okay, a previous speaker said, 260 °, I have not measured but either way the angle is sufficiently.
The so expensive batteries that are to be addressed here, the LR1. One costs about 1.70 two are needed. I drive every day by bicycle and the batteries should last times loose 60 hours.
That's me connected my safety with the design factor absolute value!
