Features: Specially designed for telescope primes focus astrophotography. One side: Standard 1.25" barrels. Fit 1.25" telescope focuser or other accessories. The other side: M42x0.75 thread C mount (1 inch diameter with 32 thread per inch) All metal framework. Threaded for Standard 1.25" Eyepiece Filters. Allows you use an astrophotography filter for better imaging experience. Capture breathtaking image of distant galaxies and planet with the 1.25 Inch to C Mount Adapter. Specifications: Material:Alloy Outer Diameter:Approx.42mm/1.65in, Height:Approx.25mm/0.98in Bottom Diameter:Approx.30mm/1.18in Color:Black Package Includes: 1x1.25Inch to C-Mount Adapter note: Please allow 1-2cm errors due to manual measurement,please make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.