This is as big as a rabbit I could pull out of my hat. the big kahuna, the commanders scope. 
I was told that this was the tank commanders periscope from an M113 Armored Vehicle. The two knobs allow the objective lens (top lens) to tilt up or down and to rotate 360 degrees. Optics are clear and clean. $4,999 plus shipping. Pictures here: http://s206.photobucket.com/albums/bb58/Skyvandelta/Military%20Periscope%20M113%20Commanders%20Scope/
Mount this in your RV, childrens fort, home bunker...
Anyone want to comment on the use or history of this item?
M113 history here: http://en.wikipedia.org/wiki/M113_Armored_Personnel_Carrier
Bradley history here: http://en.wikipedia.org/wiki/M2_Bradley
email and phone for fastest response
SkyvanDelta@yahoo.com
510.523.5031
Alameda, CA