I got this collimation eyepiece for my 8 inch Dob. As far as I can tell it works great. The reason I didnt get a laser collimator (only slightly more expensive, but not much) is because some reviews say that even a laser collimator can be slightly off. Collimation eyepieces are generally more accurate. I collimate my scope after 2-3 times usage and although generally much collimation isnt required, it is something that I can recommend as it makes it an easier and faster process relative to not using anything at all.