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! High magnification for eyepieces to see more details of the moon; bands of Jupiter clearly; SVBONY 2x barlow lens is a better choice. With T/T2(M42x0.75mm) male thread for T/T2 connectors. Barlow lens has a T mount adapter so you can attach a DSLR camera with an available T-mount. The filter is suitable for those astronomers who are already imaging using color cameras and don't want to transition to a monochrome camera set.