The all-new Raceframe Impact SB Guard is Fox Racing's top-level chest guard. The key feature on the SB version is the addition of an F3 impact-absorbing insert on the back. The F3 material is body heat activated to provide a custom fit which conforms to your back while riding. The articulated design wraps the body for unparalleled protection, flexibility, and comfort. The straps are adjustable to fit all body types, and the low-profile design can be worn over or under the jersey.