Feature:1. Scope of Application: 1.25 inch to C CS mount adapter fits any telescope C mount (male thread) telescope eyepiece changer with a 1.25 inch eyepiece tube.2. 1.25 Inch Mount and M25 Thread: The 1.25 inch mount is suitable for filters, focus reducers, and extenders. M25 external thread is suitable for C mount or CS mount camera lenses.3. Aluminum Alloy Material: Made of black anodized aluminum alloy, which is wear resistant, durable. The adapter is fully threaded inside to minimize reflections of stray light.4. Internal and External Thread Specification: External thread specification is M25x0.75mm (commonly known as C mount, CS mount thread). Internal thread specification is M28.6x0.6mm.5. Adapter Size: External thread depth is 5mm / 0.2in, internal thread depth is 4mm / 0.16in, outer diameter of mount is about 1.25 Inches (31.6mm0.1mm), overall length is 30mm / 1.2in.Specification:Item Type: 1.25 Inch Mount to C CS Mount AdapterMaterial: Aluminum AlloyExternal Thread Specification: M25x0.75mm (Commonly Known As: C Port/CS Port Thread)External Thread Depth: Approx. 5mm / 0.2inInternal Thread Specification: M28.6x0.6mmInternal Thread Depth: 4mm / 0.16inOuter Diameter of Mount: Approx. 1.25 Inches (31.6mm0.1mm)Overall Length: Approx. 30mm / 1.2inColor: As Pictures ShownWeight: Approx. 16g / 0.6oz.Package List:1 x Adapter