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 scribed line in a glass window to serve as the rear sight, and the glass is protected by an exterior guard. A brass bezel can be rotated and is marked off in 10-degree increments. The bezel has detents so you can change the heading reference a known amount without looking at the compass.A side adjustment varies the tension on the detent mechanism. The outside diameter of the compass case is engraved with a compass rose for fast determination of rough direction. The compass has a antique finish and the compass measures 2 3/8 inches (6.0 cm) in diameter, 1 1/4 inches (3.2 cm) thick, and weighs a very solid 300 grams. This compass is fully functional, but is not certified accurate. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "tmi-nuatical-mart" and is located in this country: IN. This item can be shipped worldwide.