5640-01-183-3904 (ASTM-E1264)
5640-01-183-3904 is equivalent to manufacture part number 925. It is a sound controlling block and is classified under Federal Supply Class 5640 (5640 - Wallboard and Insulation), stocked for defense, aerospace, MRO, and industrial maintenance applications. This item is cataloged in the NATO supply system under 5640 - Wallboard and Insulation and is available through NSN-PARTS for U.S. government MRO, and commercial procurement.