Flashguard, Blue Filter, SDU-5/E Strobe- Made by ACR Electronics Inc and contract dated 1995. Measures approx 3.5" x 2.5". Plastic cover stores the distress beacon inside while in survival vest to save space. The blue filter is used to change the color of the flash on the beacon so aircraft viewing it do not think they are getting shot at. Unissued condition in original packaging.