The 3x barlow lens triples the magnification of any 1.25 inch eyepiece. The apochromatic barlow lens provide a high power magnification allow you to look more closely and more detailed at the moon's surface and other planet. 2 element one group broadband green film multi coated optical glass; the housing is blackened 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;work as at adapter;connect DSLR or SLR camera to telescope easily via a separate sale t ring adapter. Connect DSLR SLR camera to telescope easily; Specifications: Material:Metal Size Chart: Size:Approx. 3.6x9.6cm/1.4x3.8inch Package Includes: 1 Piece 3x barlow lens