1M42x0.75mm Thread: M42x0.75mm thread, make sure the connection is firm and tight, and will not fall off easily. 2Matting Treatment: The inner wall of the aluminum alloy adapter rings is subjected to matting treatment to prevent the radiation from affecting the imaging. 3Male to Male: M42 to M42 rings adapter, male to male, easy to install and won't cost you too much time. 4Aluminum Alloy: Aluminum alloy material, accuracy craftsmanship, durable and corrosion resistant, can be used for a long time. 5Small and Portable: The Telescope adapter is flexible to use, small and portable, and can be easily carried and used even when going out.