I purchased one of these for my Streamlight Scorpion flashlight in early December. I have had my Scorpion light for about 10 years, and I love it. I knew I wanted to attach a flashlight to my PS90, and I already had a great one that was recoil proof.
This also allowed me to not have to spend another $100+ on a tac light. And, to me, pistol tac lights don't look as good on a rifle. On rifles, I like traditionally shaped lights...
Once I got my rails in, I attached them to the gun, and then put the light inside of this Fobus mount, and tried to put it on the rail. I soon found out that the molded plastic of the mount didn't exactly fit the rail, despite the claim that it did. 1 side of the flashlight mount was not quite wide enough - but it was close. Very close. The mount is made to fit the aftermarket rails for the PS90, but it was just a minor manufacturer flaw.
I did manage to get it on. But, it was done the hard way - I had to beat it on. Its not as bad as it sounds... I took my hammer, and folded a washcloth over the flashlight mount, so I wouldn't damage the plastic. I then succeeded in beating the mount down the rail. Of course, I removed the light from the mount while doing this. I stopped when it got where I wanted it. I then put the light back into the mount.
I am satisfied w/ it, but for the $30 cost, it should not have needed this force to get it on. I really wanted to buy a $6 scope ring to attach the light, but the Scorpion light is not 1" thick. I could have ordered a spacer that is sold on some gun websites to make up the difference. And, if I were to do it again, I'd probably do this.
Anyway - here is what it looks like on the gun: