Internal thread end: M32.5 x 0.5 thread, External thread end: M42 x 1 thread, Thickness: 5 mm. Made of aluminum alloy, stable and wear-resistant, smooth installation, no slippage or jamming. Used to convert M32.5 internal thread lenses to M42 external thread interfaces, achieving lens compatibility with camera bodies/accessories. Expands the compatibility of lens systems for attaching filters, extension tubes, adapter rings, and other photographic accessories. Lightweight and portable, simple installation, plug and play, no additional tools required.