My thoughts on the Samson Evolution free float rail:
OK, I've put this rail on two different builds for friends. I also put one on an AR15 that I've built for my son for his 10th birthday this fall (pics of that build coming soon!).
The rail attaches using a standard barrel nut. That is extremely convenient, in my opinion.
Three sides of the rail do not have continuous rails to have to cover. Nice and smooth, but not slick.
This rail is very light in weight. I like that!
The rail seems strong. Not going to say it's the strongest on the market, but I will say if you *need* something stronger, you should pay more than $200 to get it.
The rail costs under $200! (Actually got one from Primary Arms for ~$167 on sale!)
The rail comes in several lengths - including 9", 12", and 15" (those measurements are not exact).
The rail comes with small rail segments that can be attached on either side or the underbelly. I think there were two 1" segments and a 2" segment.
PS - use a bit of grease or motor oil on the barrel nut to help slide the rail into place. It will save you a ton of time and effort!