[SECURE PROTECTION] Screw directly onto the lens mount thread for a more secure fit. [DURABLE MATERIAL] Made from high-strength aluminium alloy for long-lasting use in various weather conditions. [WIDE COMPATIBILITY] Fits M54x0.75 size astronomical main mirrors or photographic sleeves with M54 external threads. [EASY INSTALLATION] Threaded design for quick and effortless installation, ensuring hassle-free operation. [SLEEK DESIGN] Black finish adds sophistication, giving your telescope a professional look.