Lagenwinkelscheibe German U-Boat Torpedo Firing Computer

This is an authentic original WWII-era German Lagenwinkelscheibe U-Boat Torpedo Firing Computer.  It was used to determine the correct firing angle from the U-Boat to the target.

A Lagenwinkelscheibe consisted of three coaxial dials: external compass dial, an internal dial, and a transparent dial with reading line. The compass dial is graduated from 0 to 360°. The internal dial is graduated from 0 up to 180° and then down to 0. The reading line has three marks which allows setting or reading the target’s true bearing, target relative bearing, and angle on the bow.  

Made of a hard plastic or bakelite, it is in it's original wooden case measuring ~6.5 inches square.  A rare find indeed.