SV136 3x barlow lens Triples the power of any inserted eyepiece: Triples the power of any 1.25" eyepiece without adding a very long extension between the telescope and the eyepiece. Work in diagonals or reflectors: Insert this into the telescope's eyepiece holder or diagonal first, then insert your eyepiece into the SV136 Barlow Many application: especially helpful for boosting the magnification during lunar or planetary observations under good seeing conditions Fully-multi coated achromatic design Minimize the reflection of light during refraction,Maximizes the saturation and contrast of image colors, and the edges of the image are sharper Superior sharpness and color correction, optical components, real physical computing magnification 2 X Free dust caps The dust cover provides maximum protection for your Barlow lens when you are not using it. Can effectively prevent dust from attaching to the lens and affecting your viewing experience Rubber grip ring SV136 3X barlow Lens has a rubber grip ring, which is easy to grasp and not easy to drop. SV135 fully multi-coated zoom plossl eyepiece zooms to any focal length between 7 mm and 21 mm - pick the better magnification for your subject. As a beginner; SV135 zoom eyepiece is good for starter astronomer! 7mm-21mm linear continuous zoom Regarding the zoom action; it is stiff enough that you won't accidentally shift focal lengths; but it is also smooth enough that you can rotate it without holding the base of the eyepiece with your other hand M28.5*0.6 filter thread SV135 zoom eyepiece has M28.5*0.6 threads on the bottom very convenient for connecting filter;Works great for photography Fully Multi Coated 6-Element 4-Group premium optical with FMC ultra high quality standard coating;It also ensures the transmission of light up to 97% while reducing the loss of light during transmission NOTE: Each telescope has its own maximum capability of the telescope optics.And after the maximum, image get blurred.The Maximum usable mag