I've used
these for years. The current ones are brighter than they used to be, but even my 5 year old is very bright. The reason I still have older ones is that they're so reliable.
I generally run daylight lights, and have been told these show up well even in sunlight, whether flashing or steady. The penalty is shorter battery life than with some other 'be seen' lights, but it's more than enough using standard 1000 mAH rechargeables. I've never got anywhere near the quoted run time with rechargeable or alkaline batteries with this or any other 2 x AAA light.