This is a brand new graduated mechanical stage attachment for AmScope M148, M149, M150, M152 series microscopes. It holds standard microscope slides. It has a center mount screw with two locating pins at 1-3/8" (35mm) apart. Its travel ranges are 1.2" (30mm) and 2.0" (50mm). Features & Specifications: Two Locating Pins: 1-3/8" (35mm) apart Travel Range: 1.2" (30mm) and 2.0.