I just googled for them. The sight on the reciever you can mount your self. On the barrel it needs to be soldered on by a gunsmith. You can buy the barrel with the sight on it already from Mossberg and then install the ghost ring yourself. I think I will buy the one from mossberg. Then I have my regular 18 1/2" barrel, my new 18 1/2" ghost sight barrel, and my 28" hunting barrel. And I don't have to hope that the gunsmith I pick doesn't mess up the solder job.