4820-33-004-4489 (8643 8918643)
4820-33-004-4489 is equivalent to manufacture part number 891. It is a valve piston and is classified under Federal Supply Class 4820 (4820 - Valves, Nonpowered), stocked for defense, aerospace, MRO, and industrial maintenance applications. This item is cataloged in the NATO supply system under 4820 - Valves, Nonpowered and is available through NSN-PARTS for U.S. government MRO, and commercial procurement.