The FIS 400x Handheld Microscope utilizes a white LED for coaxial illumination. Light is introduced into the optical path (axis) so that it comes out the tip of the objective lens and strikes the ferrule perpendicular to the endface. This method of illumination produces a high level of resolution providing excellent detail of scratches and contamination. Other features include: Ergonomic soft hand grip, eye relief boot, interchangeable connector adapters, and battery life. Microscope light switch must be continually held down for light operation.