"The SV216 Barlow lens adopts a 4-piece telecentric design; which effectively prolongs the focal length of the primary mirror without introducing chromatic aberration and vignetting problems that bother users; offers excellent spherical aberration control; resulting in a flatter field of view than standard Barlow lens The magnification of the SV216 Barlow lens is constant at 2 times; the 4-piece design of the Barlow lens and the optimized optical structure ensure that the magnification factor of the Barlow lens remains unchanged no matter where the Barlow lens is installed in the optical system SV216 2x Barlow lens adopts 3 screws design and coaxial locking device; improving the concentricity of the optical axis of the system can significantly improve the quality of captured images The 4 lenses of the SV216 Barlow lens are fully multi-layer enhanced coating; which makes the picture bright and sharp; the edges of the lens are blackened to eliminate internal light scatter to maximize image contrast The low magnification eyepiece is matched with the SV216 telecentric 2x 4-element Barlow lens; which can enjoy the magnification effect of the high magnification eyepiece while the eye relief distance is still within the comfortable observation range of the human eye 1.25-inch interface; the SV216 Barlow lens has a 1.25-inch interface; which can be installed with standard 1.25-inch eyepieces; filters and zenith mirrors to make it easy to use Brass compression ring; the brass compression ring firmly fixes the eyepiece in place without damaging the matching accessories"