This set contains a T-ring for Ca non EOS Cameras and a 1.25" to M42 T-mount. They are made of high-quality material, durable for long time use. It fits almost all Camera EOS 5d, 5d Mark Ii, 50d, 60d, 20d, 30d, 40d, 350d, 400d, 450d, 500d, 550d, 600d, 1100d, 1d, 1d Mkiii, Digital Rebel T4i, T3i, T2i, T1i, Xt, Xti, Xsi, Xs, and All EOS SLR Camera. It is very easy to use: 1. Connect the T-ring mount and T-Mount by M42 threads. 2. Assemble the set to your camera. 3. Connect the camera with the set to the telescope by 1.25" (31.7mm) excircle on T-mount. Tighten the screws on the 1.25" adapter. Make sure they are locked and safe. 4. Put on the camera and calibrate focal length te get a clear image. Package Include: 1 * T-ring for Ca non EOS SLR/DSLR ; 1 * 1.25"-M42 T-mount