GSO's 1.25" 3x achromatic Barlow triples the magnification of each eyepiece and effectively doubles the number of eyepieces at your disposal Full unit increases magnification of an eyepiece by 3x while maintaining a bright, high-contrast image Air-spaced, two-element, fully-multicoated ED lenses with excellent color correction, sharpness, and image brightness Precision-machined aluminum barrel with high-quality black-anodized finish