Collins Bus Corporation (Collins Bus) is recalling certain 2015-2019 Midbus DH500, DH516, DH400, DE416, DE500, DE516, TH400, SH416, and SH400 school buses equipped with HSM 39-INCH FB11 restraining barriers. In a hard braking situation or vehicle crash event, the barrier may not properly restrain an unbelted seat occupant. As a result, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 222, “School Bus Passenger Seating and Crash Protection.”