Meet Swerve: a superior tail light for your bike from Princeton Tec. Uses two high powered LEDs a combination of a diffused lens and a collimated focused lens creates a very bright 180Adeg beam pattern that alternates between a wider beam and a narrow beam. Because the eye must juggle the wide and narrow beams it doesn't get a chance to relax, resulting in a very high level of visibility. Toggle switch extends beyond the perimeter of the light and allows for easy operation while riding. Toggle switch is on a pivot: off is the middle position, down is a flash pattern, up is for steady light. Mounting options: handle bar, seat post, seat stay, and fork mounts are included. Built in clip allows for attachment to your helmet, pack, or messenger bag. Requires 2 AAA batteries included.