I bought one of those when they had them on sale for about $8 recently. Hate it. The strap system is awkward on the headlight, and there seems to be no reason to have an external USB charger that can get lost. The tail light is a little better, but still uses the same charger. Mine does not always recognize after charging that it has been removed from the charger and continues to flash periodically.

I'm much happier with this Axion headlight & tail light. About the same size as the flea, but the headlight is slightly brighter, the strap system works easily and they have a mini USB socket built into them for charging. The headlight is a "be seen" type, however. I just compared it to a flashlight that is rated at 50 lumens, and the Axiom is at least 50% brighter.

For lights to see by, I have a 200 lumen Cygolite and a 150 Lumen Nightrider. Plenty bright and relatively cost effective, especially on sale.