Aperture 60mm achromatic doublet lens, focal length 700mm Material: crown and flint Glass High density glass used pitch polished 25 mm eye pcs Pullox Telescope Making Lens 60mm with Eye Pcs achromatic Astronomical Telescope Making Lens Doublet Lens Focal Length 700mm Aperture 60mm achromatic doublet lens, focal length 700mm. Material: crown and flint glass. The high-density glass used pitch polish. 25 mm eye pcs. Useful Useful for many physics classroom demonstrations and experiments. Great for a variety of optical bench ray box experiments, exploring the refraction of light, and for comparing converging and diverging image formations. Moderate-Power Observations A great 25mm focal length eyepiece for moderate-power observations of the Moon and planets of the solar system. The 25mm provides crisp views of many deep-sky objects such as nebulas and star clusters. GREAT FOR PHYSICS CLASSROOMS This optically true lens is excellent for physics classroom demonstrations in optics and light refraction. Made of high quality optically worked glass. Highly polished with ground edges. PERFECT PITCH POLISHED THIS PERFECT PITCH POLISHED lance will provide you with a clear sharp image of any object it will help to u teach theory making telescope to your kids they can make refactor telescope. Doublet Lens Focal Length 700mm You can enjoy watching the moon surface even the craters of the moon, Jupiter with the help of this lance if u have good eye pcs. Good for Homemade Telescope This lance will perform very good with help of this lance and eye pcs telescope which can show astronomical objects as well as celestial objects .60mm achromatic doublet lens,700mm f.l. and 25 mm eye pcs focal good for those who want to make a homemade telescope.