The value must have 2x barlow lens doubles the magnification of any 1.25 inch eyepiece The apochromatic barlow lens provide a high power magnification allow you look more closely and more detailed at the moon's and other planet 2 one group broadband green film multi coated optical glass;the housing is to maximize image contrast;both that gets high quality observation without additional chromatic aberration;make image more crisp and sharp Quality aluminum stock and black anodized body with M42x0.75mm thread Connect DSLR SLR camera to telescope easily;