4240-01-128-4711 (ANSIZ87.1.4.25)
4240-01-128-4711 is equivalent to manufacture part number 428SP. It is a welder's helmet lens and is classified under Federal Supply Class 4240 (4240 - Safety and Rescue Equipment), stocked for defense, aerospace, MRO, and industrial maintenance applications. This item is cataloged in the NATO supply system under 4240 - Safety and Rescue Equipment and is available through NSN-PARTS for U.S. government MRO, and commercial procurement.