SkyWatcher Newtonian Collimation Eyepiece
Sky-Watcher Collimation Tool looks just like a normal eyepiece but without lenses, it has a small hole in the centre and a large opening at the side.
This special eyepiece is able to fit into 1.25" focusers or diagonals. the alignment process is easy using the small opening on one end and thin cross hairs at the other end. Generally, Collimation Eyepiece is more accurate compared to the simple Collimation Tool.