It's called "Quick Flip™ FFS-EXT - Railed Gas Block Folding Front Sight".  It looks like it made specfically for the gas block with rail, which is exactly what I'm in the market for.  The pictures on the website don't show much and from those pictures it's hard to tell if it actually folds or not.

I have their standard FFS model which look like it is virtually identical to the FFS-EXT in operation.  I like my FFS, it seems to be very sturdy and well built but I have not had an easy time adjusting for elevation.  My front sight tool does not fit between the openings of the hood and the curved surface at the bottom of the hood makes it difficult to rotate the post with a firing pin or something similair.  

I had a very limited amount of time with it on the range and didn't have a tool that would allow me to adjust it for zero but obtaining a good sight picture was very easy and I was able to hold 1.5" groups with it at 75 yards.  Unfortunately the groups were 8" lower than my point of aim but I'll get that taken care of next time out.

In a nutshell I'd give it a big thumbs up, well made, poitive flip up spring, solid locking mechanism and improved (in my opinion) sight picture.  I'd recommend it.

I've owned the Troy, Pri, and now the Samson.  Samson is my favorite so far.

Thanks.  I'll be ordering one probably next month!

Quoted: We were the ones that convinced Samson there was a market for this version. We sell a ton of Stag and Sabre uppers with weaver gas blocks and no front sights. This is an excelent solution for those of you that run this set up but still need a BUIS. TalonArms.com

Rob,

I would presume that it's only offered in 3/4" (.750) barrels... Any plans for the 5/8" (.625) A1 types?