From my blog: http://tv-presspass.com/tavor-trex-rail-review/
Through my years shooting the Tavor, many different people have suggested a six o'clock rail to be a great upgrade for the rifle. Personally, I like the factory hand-guard quite a bit: An integrated hand-stop, solid texturing, and natural angle are all good things as far as I'm concerned. But I can see the appeal in more rail space, especially when you start looking at bipods and wanting to plant yourself down on the ground.
As of writing, there are 3 primary options to add a rail onto the Tavor factory hand-guard. Swapping the entire foregrip is possible too, but that's another article.
1. The Fab Defense aluminum rail. Created long before the Tavor was available in the United States, the Israeli company Fab Defense produced an aluminum rail designed for the TAR-21. However, every person I've ever met with a civilian rifle has had to drill, file, or otherwise modify their hand-guard to fit the Fab Defense rail. Permanent modification is not my cup of tea. The possible advantage here is that these rails appear to fit flush right out to the tip of the hand-stop.
2. The IWI US polymer rail. These factory rails fit flush to the hand-guard with a single screw, and are quite prominent in lots of IWI's marketing. That being said: I have never seen one on the shelf of any of the US or Canadian gun shops I visit. They seem to be available on a few select sites online. While I have no issues with polymer (I mean, I'm a Tavor owner after all!) these rails have always felt a bit rough when I've handled the prototypes at past Shot Shows. At $25 they are certainly affordable, but not something I'd personally use. Some interviews with IDF personnel have suggested that rail and grip "sometimes breaks" and is one of the only complaints about the TAR platform. It's not clear whether the IDF issued rail and the IWI US rail are the same though.
3. The TREx rail. Produced in the US, and designed specifically for civilian rifles, this rail has really impressed me. I like when I can see and understand how to install something without needing to read the instructions. The TREx aluminum rail mates to the Tavor fore-grip in 3 places with a single screw, and can be installed without removing or modifying the hand-guard whatsoever.
Like any foregrip rail, this system allows you to mount a bipod or a vertical grip onto the hand guard of the rifle. I’ve never been a big fan of the vertical grip hold that shows up in various marketing materials from IWI, but having tried it for the first time this month I can see why it might be desirable in some cases.
You could also put a light on there. I’m a big fan of Inforce WMLs, and mounting one on the TREx would put the switch in an easy position if you’re using the carry-grip up against the angled portion.
If Surefire is more your cup of tea: I’d suggest looking at one of the replacement hand guards from Gear Head Works or Manticore Arms that have dedicated space for surefire lights and tape switches. Personally I like spending less than $200 and getting a stellar weapon light.
In the same vein, I like that the TREx rail is only $60 and easy to add and remove. I wouldn’t say the TREx rail is a “must-have” upgrade for every Tavor owner, but if you’re looking for a hand-guard rail its certainly the best choice.