Hi All!
A month ago, I ordered an LED blinky off eBay to attach to my helmet, figuring the higher vantage point might result in greater visibility in traffic (I have to negotiate a short stretch of dense urban traffic and cross two highway on-ramps if I want to take the most direct way as I travel north from my home). Astride my bike, my helmet is about 1.8m/6ft above the ground, easily visible above the average sedan and through the windows of taller SUVs, crossovers, and pickup trucks.
It arrived a couple days ago. After wanting a helmet light for the last 35 years to augment my bicycle-mounted lighting, I seem to have found it in a COB LED. A COB ("Chips On Board") packages multiple LEDs on a circuit board behind a diffuser or diffraction screen so they appear to be a single lighted panel. They don't have much throw, but they are very bright and also fairly large so they avoid the pitfalls of point-source illumination and provide the viewer with enough visual reference to fairly determine how far away the light is.
I prefer user-replaceable batteries so I can swap in new cells to replace depleted ones on long day (night) rides, so I looked for a COB LED helmet light that used AAA cells instead of embedded rechargeable batteries. I found one design that was both very lightweight and cost only USD$3 incuding shipping. It is bright enough to be easily daylight-visible, attaches with a gel strap that holds securely and doesn't hurt the helmet mounted to front, rear, or both, and has five solid/flashing modes in red and/or white. If you want the same kind, search for eBay vendors selling "COB LED helmet light" and check the description to make sure it uses AAA cells. Mine can be mounted in any of four orientations and has a spring-loaded ratchet to aim the light vertically or horizontally. Mine holds securely, but I feel confident it would deflect or detach safely in an accidental fall. The same light(s) will attach almost instantly and just as securely to seatpost, handlebars, or frame.
I haven't owned the light long enough to determine practical battery life. I intend to use it only in more congested traffic and might even detach and store it in my handlebar bag or a rear jersey pocket till it is needed. I'm powering mine with Eneloop rechargeables and it works fine so far. I do wish the light had more red-only blink variations, but I'll probably use it in solid-red mode most often. I think the red-white combo is most visible but also most confusing and even illegal ("white light to rear prohibited"). The solid white on the front provides a nice, diffuse light to read maps on my handlebar bag or check my computer readout at night. Nice.
Photos below showing mine attached to the rear of one of my helmets. For videos of my example blinking in all modes and colors, go here:
Front:
https://drive.google.com/open?id=1MyFpvFzSCUBoD8iJmt-J-3UumWaLPCysRear:
https://drive.google.com/open?id=1YmhjWZnebSdrOePQBL6x_oMzctJMaAXRBest,
Dan.