A genuine U.S. SDU5/E distress light marker & blue filter. This SDU-5 was made by Fedcap Rehab SVCS NY US and is dated 1998 with SPO (System Program Office) contract number, marker is in working order and BA-1574/U Mercury battery still has a charge in it. Switch activates a bright strobe flash for identification. Comes with a blue flash guard filter used to prevent friendly fire incidents as the strobe flash could appear to look like a muzzle flash, guard has a DLA (Defense Logistics Agency) contract number and is dated 1983.