Worked terrifically for 1-2 months of dry use. Once Fall rolled in and I went out on a rainy century it was totally unusable. Would not turn off. Then the small on/off button fell off (looks like it was held on only be an adhesive? Also noticed water has seeped into the light and some odd liquid has seeped out and dried. Again, I assume some sort of adhesive? It could not stand up to one long rainy ride, but worked really well for my commutes and rides up to that point.
The light is very visible all around and a bit too bright. Too bad unable to customize brightness but only the blink pattern with the app.
The medium size is a bit bigger then I imagine