3" Inches Approximate Military brass compass solid brass engineering prismatic compass easily folds and the lid opens and the front prismatic sight folds over the compass to function as the front sight. The prism has a magnifier to allow viewing the compass card and the object being sighted simultaneously. The height of the front prismatic sight can be adjusted to focus the compass card. The lid has a scribes line in a glass window to serve as the rear sight, and the glass is protected by an exterior guard. The cardinal points are luminous for easy viewing in the dark, and the compass features a standard glass bezel with two lines at 45-degree angles. The bezel also rotates with detents so you can change the heading reference a known amount without looking at the compass. The front sight has a magnifier to simultaneously view the magnetic heading when taking a sight. Folding the sight down operates a needle lift mechanism to protect the compass bearing. On the side of the compass is a needle freeze mechanism to hold a reading. Antique collectible magnetic compass very nice for marine gift