It is a type of personal protective equipment (PPE) designed to enhance the wearer's visibility in low-light or hazardous conditions.
The bright fluorescent yellow/lime color and reflective strips help signal the wearer's presence to others, especially in the light of vehicle headlamps at night.
Commonly used by workers in construction, road maintenance, law enforcement, and transportation industries to prevent accidents.
The item in the image features a zip closure, multiple pockets, and a D-ring attachment point.