Robust construction with aluminum alloy Built from an aluminum alloy for strength and reliable performance in the field. size for astronomy enthusiasts 25 inches long, designed to fit most astronomical telescopes and integrate smoothly into your setup. Essential for optical alignment Aids in calibrating the optical axis of reflective telescopes, helping you achieve better focus and more consistent results. Improves observation quality Includes a 45degree plate that enhances visual accuracy across different viewing angles, improving the overall viewing experience. Compatibility and practicality Fits most astronomical telescopes, making it a versatile tool for alignment and maintenance. Use scenarios Before an observing session: use to align the optical axis for crisper, more accurate focus. After transport or servicing: recheck alignment to prevent degraded image quality. While observing at different elevations: the 45degree plate maintains accuracy across various viewing angles.