an apparatus for providing deceleration rate information of a user operating a vehicle is disclosed . the apparatus includes a unit including an accelerometer , a processor , and a lighting mechanism . the processor receives from the accelerometer deceleration info of the vehicle and variably adjusts at least one aspect of the lighting mechanism , thereby quantitatively signaling the deceleration rate to a driver of a following vehicle . the unit may be mounted on an article of clothing , a bag , or the vehicle itself .