Features: Provide focal length option of 4mm, 10mm, and 23mm to meet different observation needs, allowing users to have a wide field of view or high magnification. The surfaces of the lens is treated with antireflective film, which can reduce reflection and scattering, provide clear and sharply images, and make observations more accurate and detailed. Make from metal materials, it is Enduring and have long lifespans, suitable for long terms observation use. Easy to install: With a 1.25inch standard interfaces, it is suitable for most astronomically telescopes, making installation and replacement easy and quick. Suitable for enthusiasts, astronomy students, amateurs astronomers, and professional astronomers interested in astronomically observation. Specifications: Materials: Metal and optical glass Styles: 4mm/10mm/23mm Size: As shown in the picture Note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color. Package includes: 1pc Astronomy Telescope Eyepiece