CatEye's TL-LD150 Taillight features 5 ultra-bright LEDs for excellent visibility, flashing and steady modes, and runs for up to 90 hours on the included 2 AAA batteries. Plus, it includes a no-tools universal mount and a clothing/bag clip.
Run time in hours: 45, 90, 90 (constant, flashing, random flashing)
Weight in grams: 48
Battery: 2 AAA (included)