The best at it's price point, if your looking for a quad rail. - UTG Pro AR15 Free Float Quad Rail

This handguard is well designed and easy to install. It looks great on the rifle. And is lighter than most other quad rails. The strongest thing about this is the price to quality ratio. There is much more quality than you are paying for. The last pro is that it is American made. Too many people don't give UTG their props on this little fact.

Now to the only con I could find. The mounting hardware is cheap and will strip if you torque them to anything that will hold the guard on through extended use. Two of the screws stripped the first time they were installed. One screw required the use of an EZ out. My advice is to not even use the screws that are included.
Here are the replacement sizes; 10-32x1", 10-32x1 ¹/⁴". Get stainless or phosphate socket cap screws and you'll be fine.

Honestly, the review would be 5 stars if the included hardware was better quality.