It's better than I'd dared hope for my particular needs. I don't know anything about the seatpost attachment components, as the option I needed/use is the "belt clip" style attachment that's part of the light itself. I clip it to a webbing loop on the back/rear of my under-seat bag, and from that location, it gives an excellent view to traffic. I don't routinely ride after dark, but wanted this light for increased safety for daylight riding and into dusk on occasion. Especially for the modest price and light weight, I'm really impressed with how bright this tail-light is, and the several different types of "flashing" light options in addition to solid "on".
Hi -- the Lezyne Fusion Drive Pro 600+ Front Light is a good option. It has six settings (which is good), well engineered and strong, the smallish size in length and width is great, and the face of the light (5-led bulbs) gives good viability during the day and when I use it at night (which is often). This light is bright enough at night -- I never use the 600 lumen setting.
I am not a fan of the way this light attaches to the handle-bars, because you have to unhook the whole light in order to recharge it. I commute 5-days a week and find myself recharging this light about every 2.5 weeks.
I use this on nearly every ride, unless I'm purely on singletrack, and it's been so useful for detecting traffic that I can't imagine living without it. When my first one died after years of use, I bought another one the same day. It's especially helpful on gravel roads when it's hard to hear rear approaching drivers, and it's also invaluable when riding and chatting side by side, since it saves us from having to constantly look over our shoulders. Sometimes I think that drivers should buy these for all cyclists because we probably get over so much quicker, when appropriate.
I use this in combination with a helmet light with less brightness. It is very bright and the field of vision at night is strong enough for dark gravel trails or dark streets or even wooded trails. The battery life is okay on the highest setting, but you will have to recharge it every hour or 90 minutes if you have to use it on its highest setting.
I also have the Lezyne Micro Drive 800 Front Light, and that was not as good for the toughest, darkest situations, which is why I upgraded to the 1000+....
