1、Size Standard: The diameter of the dust cover is 42mm, and the thread is 0.75cm. Real machine 1:1 mold opening is suitable for astronomical primary mirrors or photography sleeves with M42 external threads in the size of M42x0.75. 2、Easy to Use: The internal thread design of the dust cover can be directly screwed onto the thread of the lens interface, making it less likely to fall off compared to a closed dust cover and more secure in protecting the lens. 3、Lightweight and Portable: The dust cover weighs only 13 grams and is a lightweight structure, which can be used indoors or carried outdoors without any burden, making it very worry free. 4、Durable and Wear Resistant: The lens cover is made of premium and durable aluminum alloy, which is wear resistant, not easy to wear out, and has good weather resistance. It can withstand any extreme weather and has a long service life. 5、Protecting the Lens: This dust cover can prevent dust from falling on the lens on the one hand, and also protect the lens from collisions and extreme weather.