Laser bore sight - Firefield Laser Bore Sight

I have a couple of these and I kinda prefer this type of bore sight over the type you put in the end of muzzle, not that they don't work cause I used those for a couple of years before I started using the chamber style, I just seem to like these better because you don't have to worry about loosing any of the little screws you need to put on your various size adapters or the adapters themselves,I for that reason like the chamber style better.