The Aven Tools 26800C-534 40x Pocket Microscope is the ideal carry-on microscope with magnification of 40x. its eyepiece has a scale with 0.1mm graduation and a measurement range of 4mm. The microscope furthermore has a built-in light source. In addition, a clear acrylic stand allows ambient light to reach the object under examination. The microscope operates on two AA batteries (not included). It is ideal for on-site detailed examination of small areas and objects. It is especially useful for engineers, tool makers, quality control inspectors, and field researchers.