The SV231 1.25‘' color correction filter is designed with full thread and standard size to compatible with different types of telescope. High transmittance means high level of transparency, allows a significant amount of light or energy to transmit through it. You can use the SV231filter with SV48P telescope for astronomical observations without color difference to obtain the most exquisite details of lunar craters and planetary surfaces. 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! The SV135 is stiff enough not to accidentally change focus and smooth enough to rotate without having to hold the eyepiece base with your other hand. 7-21mm which will give you a wide range of magnification options. This is especially useful in lunar observing where one short barrel twist at a time will bring you closer, closer, and closer still to the Moon's craters and mountain ranges to the point where you get the feel of looking down at the lunar surface from an orbiting space station.