A Svbony SV121 laser collimator features two O-rings on its 1.25" barrel, ensuring that it sits securely and centrally in the focuser of a Newtonian telescope without wobbling.
The laser collimator has an all-metal construction, and its brightness can be adjusted in three levels, allowing the intensity of the projected dot to be easily adapted to the observing conditions.
The advantage of laser collimators is that they can also be used in the dark, while the returning laser beam remains visible through the window on the side. This is also useful when adjusting the primary mirror at the rear of the telescope. It is particularly advantageous for longer Newtonian telescopes, as unlike with collimation eyepieces, you do not need to look through the eyepiece to see the effect of the adjustment.