1Inner Thread Design: The telescope lens dust cap is designed with internal threads and can be screwed directly on the thread of the lens interface to protect the lens more firmly. 2Versatile Use: The telescope lens dust cap cover suitable for astronomical primary mirrors or photographic receptacles with M42x0.75 mm size threads, also ideal for telescope eyepieces and telephoto zoom eyepieces. 3Convenient and Practical: The telescope dust protective lens cap can effectively protect the telescope eyepiece from dust or dirt, excellent performance, safe and reliable. 4Aluminum Alloy Construction: The telescope protective lens cap cover is made of aluminum alloy, lightweight and durable, reliable and sturdy, easy to use. 5Easy to Install: This telescope eyepiece dust cap can be easily installed on your telescope. Simply screw it onto the lens or eyepiece and experience hassle free protection.