These flip-up training glasses feature an improved design that lets you effectively and easily communicate with your student or instructor. Plus, it feels good on. They fit nicely under headsets, and the Velcro strap means a secure but not-too-tight fit. Transition smoothly from IFR to VFR with a flip of the lens. The lightweight polycarbonate lens is impact resistant and designed with a quick release hinge feature for safety of flight purposes - so as to provide another quick way to remove the lens obstruction. While overall quality rating is very high, if the eye cover lens falls off during normal operations, including turbulence, or if the hinge breaks, then they should be sent in for replacement. Jeppesen needs items returned for replacement so that we can correct any potential defects or determine if glasses were somehow damaged during shipping or use.