British WWII Clinometer Mortar MK IV Target Level

British WWII CLINO (clinometer)  Mortar (MK IV) target level made by the B. I. Co. Ltd. as engraved on the corner of the sight. Adjustable sliding sight on a semi elliptical track, with "TARGET" engraved on both sides  with an arrow pointing toward the front of the instrument. Target arc from 0 to 90 degrees. Measures 7.75 inches. Also marked Reg. No. 14961 and dated 1944 and has a broad arrow proof mark. The device operates with an intricate Spirit bubble level that slides along a precision machined track, when the bubble lines up in the cross hair lens, an angle setting can be taken.