The PCT120 is a versatile upgrade for B120, T120, and M620 compound microscopes. It provides all of the tools necessary for use with phase contrast and brightfield. Phase contrast is used to reveal detail in indistinct objects, such as unstained cells and microorganisms that would otherwise appear invisible. By using a combination of specialized objective lenses and a modified light condenser, these invisible objects can be visualized by manipulating variations in phase. This contrast method provides far more detail than darkfield. The turret condenser not only provides the annuli needed for phase contrast, but also a brightfield setting with an iris diaphragm. This versatility makes life a lot easier by allowing you to switch between lighting methods by simply rotating a dial. The turret has two centering screws for proper alignment of phase-contrast settings. A telescopic centering eyepiece is also included for precise alignment, guaranteeing optimal results. Four plan-achromatic objective lenses are included, each equipped with a phase ring. These provide sharp, high-contrast images at magnifications from 10X to 100X. Condenser Mount: 37mm bottom mount Model Compatibility: B120, T120, M620 Condenser Type: Turret design with phase contrast and brightfield Numerical Aperture: 1.25 Immersion Medium: oil Centerable Annuli: yes Phase Contrast Positions: 10X, 20X, 40X, 100X Objective Lenses: --10X plan-achromat NA 0.25 --20X plan-achromat NA 0.40 --40X plan-achromat NA 0.65 --100X plan-achromat (oil) NA 1.25 Contents: One turret condenser Four objective lenses (10X, 20X, 40X, 100X) One centering telescope One green filter