This headlight arrived today, isn't a bad purchase overall, particularly because it's now about £1.50 cheaper. Is it worth the asking original price? Hell no.
It's horn function is terrible, low volume awful buzzing noise - I doubt it'd alert pedestrians even if you sounded it directly behind them. Worse, the horn switch connects via USB-C, so you have to keep it's rubber flap open, which will let in rain. I continue using my Hornit Mk1 140db instead.
The last time I used battery powered headlights was in the 1980s, and this headlight is a much brighter than those twin AA powered things, but not as bright as one of my ebike battery powered "1800LM". I haven't tried it on the road yet, but I think this is a light for increasing the odds of being seen, not so much for seeing potholes with. It has a full sized USB port on the back, serves as a power bank, can be unclipped and used as a torch. The box says it contains 18650, doesn't say how many but it's small so probably just the one? Repairable probably in a year or two, or whenever the cheap Chinese cell(s?) it undoubtedly contains dies a death.
From a full charge at highest of three brightness settings, constant, it lasted 3 hours and 41 minutes. Lower power modes are available. This is for my acoustic bike, so 10 minutes would have been enough.
I'm rather more pleased with this laser rear light:
On it's downward pulsing line effect mode with flashing lasers, it's still going over 3 hours later. Well worth buying, especially now that it's reduced in price. It's brighter than the laser blinky flasher it replaces, has more than twice the number of frickin' laser beams, well worth the money. The only thing I don't like is the positioning of the charging port - it's on top! That rubber flap isn't going to keep rain out! Stupid positioning for a charging port. I'll have to protect it with gaffa tape or something. If it's mount could rotate, it would have replaced the light on this, but pointed down for the lasers to project on the tarmac to my right.
EDIT: I've just now discovered that it can replace the thin horizontal light on the Guerney Siderating Illumimaker™after al - it's octagonal at the back, can be mounted at 45, 90 degrees etc. I'll have to use it's constant mode, to prevent it being mistaken for an indicator.