Blackburn Mars 4.0 rack-mount rear flasher - $29.99
"Just be careful when turning this one on...it's BRIGHT!!!"
- Small, compact and packs a wallop with a ultra-bright 1-watt red LED
- Side visibility with 2 amber LEDs
- Easily attachs to bike racks, belt clips and most bikes
- No-hassle, no-tool battery access
- 2 AAA batteries run 50 hours, 150 hours in flashing mode