Affordable and lightweight. Has a very long life span, haven't needed to use the extra pack yet, but nice to have the assurance if needed. Would recommend getting an extra for those long rides. Charges fast as well which is a big plus.
I purchased this battery to use with a cheap mountain bike light that I got from amazon. I converted this light into a helmet light and was brighter than either of my friends Trail Tech HID lights. The light has 5 Cree XML2-T6 LEDs and has a Chinese lumen rating of 6000lm (more like 1500lm).
At any rate the 6x18650 battery pack that came with the light lasts 1 hour 8 minutes before it shuts off. This battery pack which Task just updated to use 2 Li-Po cells lasted 4 hours 18 minutes of continuous run time. The last 12 minutes the light had a red light on the back. Using the Task battery pack the light also was brighter for longer compared to the provided battery pack. If you have an 8.4v light this is the battery pack for you!