Kollsman Sextant Aircraft Periscope. Model MS28011-1. Probably for the US Air Force. " US PROPERTY 31276-1A". Patent USA NO. 2516187. Kollsman Instrument Corporation Stock Number R88S0400-050-000. Order Number N0a(s 51-087). Mfg. Serial No. aF52-2644. Mfg. Part No. 1471B-01. Specification MIL-S-5807A. 28 Volts AC or DC. MS Part No. MS28011-1. Has a timer that works perfectly. It winds with a push of a lever, operates with a push of a button for a limited amount of time. I think it is about 1 minute. No cords, accessories. Rubber eye piece included but in rought condition. (I found it just today so it is not in the photos). Let me know if you want a picture. Very good to excellent condition. A little dusty. Appears to work fine. Minor wear on prism and glass but no damage and you can see crystal clearly! One small dent near the base of the large tube. Dent measures 1/4" x 1/32" depression w/ missing paint. See photo. Does not effect operation of the unit, cosmetic damage only. PERISCOPE HAS AN ADJUSTMENT FROM 0-100 DEGREES SO YOU CAN LOOK STRAIGHT IN FRONT OF YOU OR STRAIGHT UP. FOCUS, TIMER, DIALS, LEVERS ALL SEEM TO FUNCTION PROPERLY. GREAT ITEM! Measures 15" long x 6" wide x 8" deep. Very well built, quality unit. Weighs about 6 lbs. Will last many more years! SEE PICTURES & LET ME KNOW IF YOU HAVE ANY QUESTIONS.