This set contains a T-ring for Nikon Cameras and a 1.25" to M42 T-mount. They are made of high-quality material, durable for long time use. It is very easy to use: 1. Connect the T-ring mount and T-Mount by M42 threads. 2. Assemble the set to your Nikon 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 Nikon SLR/DSLR; 1 * 1.25"-M42 T-mount. With Astromania Alignment 1.25" Next Generation Laser Collimator 2" Adaptor for Newtonian Telescopes you will get perfect alignment of your reflector's optics, and faster than with standard collimators. Precise collimation ensures that you will enjoy the sharpest possible images.With this Laser collimator get the best image from your telescope you need to align your telescope regularly and this high quality laser collimator is an essential for this purpose. 1MW or 5MW red laser Seven adjustable brightness levels 1.25" in size. To use for all reflective telescopes 45- degree reticle plate made of aluminum for easier visual accuracy. The battery is not include.