2.5" 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 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 fre 2.5" 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 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 gifteze mechanism to hold a reading. Antique collectible magnetic compass very nice for marine gift