Pelikan 360°, Full Round Protector

The image you've shared is of a Pelikan 360° Protractor (Model R-513). This is a full-circle protractor, which is particularly useful for measuring reflex angles (those greater than 180°) and for tasks involving circular geometry or navigation.
Key Features:
This specific model has several distinct markings that help with different types of measurements:
• Outer Circular Scale (0° to 360°) : This is the primary scale for measuring angles. Unlike a standard 180° protractor, you can measure any angle in a single step without having to add values together.
• Inner Numerical Scale (1 to 12): : These numbers (located just inside the degree markings) are often used for dividing a circle into equal parts or for specific technical drawing applications, such as representing hours on a clock face or compass points.
• Center Ruler: The horizontal bar across the middle features a metric scale (in centimeters) extending from a center "0" point. This allows you to pinpoint the exact vertex of an angle and measure distances from that center point simultaneously.