Hard-coat black oxidation surface treatment (MIL-A-8625) for durable, corrosion-resistant performance. 1.25"/31.7 mm standard eyepiece compatibility to fit a wide range of eyepieces and accessories. Constructed from 6061-T6 aluminum alloy with M42x0.75 mm threading (68-1 compliant) for secure, reliable attachment to general telescopes. Adjustable eyepiece position to help you achieve a sharper image by fine-tuning eye relief and focus distance. Compatibility: supports all types of telescopes, including reflector and refractor, for versatile use. Applications: ideal for observing star clusters, the Moon, planets, and other celestial bodies. Use scenarios: - Planetary viewing with a standard 1.25" eyepiece, adjusting position to maximize sharpness on the target. - Star cluster observations on a reflector or refractor, leveraging broad eyepiece compatibility. - Field use with quick eyepiece changes while maintaining secure attachment and accurate alignment.