Anyone know what the was used for. It is off an aircraft. The connecter that hooks to base is to be PL-106 There is a zero set knob and two spline drives marked A and B. Also the number 101 stamped on the the bottom of base. The loop is 8 1/4" dia.. Itseems there would have been some type of canopy cover bolted over the top. I don't have the cover.