Unlike other chest protectors the UFO reactor offers collar bone support, the Reactor Evolution is designed to be suitable for use with the Leatt neck brace. extremely light, anatomically-designed and can easily be worn under any kind of motocross jersey, Reactor has a special up-and-over system (Flex System) titling both the front and the back parts when necessary this provides optimum freedom and movement with its flex system, One size fits all, CE Approved, Made in Italy.