Empire® small angle magnetic protractor features a durable Polycast® construction that offers long lasting durability. It has full view acrylic vial protractor dial is graduated in 5° increments for added convenience and comfort. Magnetic base, full view acrylic vial protractor dial is graduated in 5° increments. Durable Polycast construction. Empire® 361 Polycast® Magnetic Protractor with Acrylic Vial, Durable Polycast® Construction, Imperial