Missing thread on the sight. - Meprolight Tru-Dot Shotgun Night Sights for Mossberg Shotguns

After reading the reviews I thought it was a safe bet, so I purchased three. I should have just stayed with the bead sight and saved my time and money. I expect better quality from Meprolight. I thread the front sight on with ease and went to make sure the sight was straight and lined up on the firearm. I then realized that the front sight was spinning freely. So I unthreaded the sight and check the my inside diameter thread no problem there. So I check the outside diameter thread on the sight and the threading located closes to the base of the front sight is none existent. So if you want to spend $30+ on a shotgun sight, install it and realize it's a piece of junk and that it will most like fly off the end of your shotgun once fired then have to take the time to remove the sight and replace it back with the original bead sight then this is the sight for you. The one star is for the tritium by the way.