This product is use coaxial to tighten, the inner ring with PETF material, it can quickly synchronous locking,And it does not hurt to the eyepiece and other accessories. This handy hybrid adapter lets you use your older 2Inch (50.8mm)/M42/M48 format eyepieces in your modern telescope that normally accepts only 1.25inch format eyepieces. This adapter allows the use of 2Inch/M42/M48 eyepieces with telescopes that normally require 1.25inch eyepieces. Fits all types and brands of telescopes with a 2Inch/M42/M48 focuser. Type:A:2Inch to 1.25Inch/B:M42 to 1.25Inch/C:M48 to 1.25Inch Colour:Black & Red Material:Aluminum Alloy Package Contents: 1 * Telescope Eyepiece Interface Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.