The world’s first motorcycle helmet with a built-in rear-view mirror system will be available in early 2006. Designed over a period of 10 years by Reevu, a UK company, it will be manufactured in Italy. The helmet employs unbreakable mirrors in an integral optic system known as MROS (Multiple Reflective Optic System). The optic system itself is made from bullet proof ABS, which is much lighter and safer than glass or metal, yet is virtually unbreakable. According to Reevu the helmet meets all international safety standards and is of a similar size and weight to conventional helmets. Retail price is expected to be $399.
The rider’s view is shown in the below photo. More information and photos at: Reevu.com

Edited: webBikeWorld posted a review of the Reevu helmet.
