Lens uses high-grade optical glass to achieve a clear views and excellent contrast 1.25" Diameter(31.7mm) eyepiece for astronomical telescopes Under fully multi coated lens can a real color reproduction and no color distortion;let you enjoy a clear and bright images Aluminium drawtube with undercut on the lower barrrel and a metal rings that is both attractive and practical Focal length: 4mm/10mm/23mm optional, you can freely observe objects with different distances and sizes, Manufacturer: SkyPOOU