SVBONY eyepieces are used to increase magnification to ease viewing Beautifully made with machined housings. The metal body gives you a different metallic feel experience. 62 degree ultra wide field of view. Maximum detail and definition across the entire field of vie;get high definition and a virtually distortion free image.The structure of the optical system. Aspheric eyepiece designed primarily for planetary observation and perfect for deep sky objects. built-in black extinction thread. SVBONY 23mm telescopes eyepiece has black extinction thread, which can reduce the interference of other light, and make the observation effect more better. FMC broadband multiple coating for high light transmission. Equipped with a precision-made standard 1.25-inch lens barrel that is compatible with any telescope that accepts 1.25-inch eyepieces. 4mm lens only weighs 0.09lb; For lenses with the same refractive index; the 62 degree aspheric eyepiece is thinner and lighter than the spherical eyepiece;designed primarily for planetary observation;perfect for deep sky objects. The SVBONY super 1.25" 40 mm plossl eyepiece engineered with 4 element design and offers a generous 40 degree apparent field of view. It is awesome for perusing the sky and finding things like constellations, clusters, and galaxies in the field of view. The built in rubber eye guard enhances viewing by helping to block out ambient light and position no introduction of additional color for higher magnification;highly achromatic 1.25 telescope eyepiece; Effectively reduce chromatic aberration and improve imaging clarity. enhance the details of planetary filters.It can be removed for eyeglass wears and astronomy photography.