This is a custom rail attachment from Custom Gun Rails Inc. They are small rail covers of laser engraved, abrasion- and solvent-resistant thermoplastic bonded with a hard coat anodized aluminum insert. There are several designs available.
They attach to your rail using two side tension screws that apply pressure to two locking tabs. The company advises there is no metal to metal contact, which mitigates heat transference and prevents damage to the rail. They're less than 3" wide and weigh 17 grams (which they compare to the weight of three nickels). They are made in the USA and cost less than twenty bucks each. The snap on clamp used by CGR is patent pending and allows you to place your custom rail guard anywhere there is space available (unless you're a certified level 13 Mall Ninja and you have no space on your rails left). They will fit on any milspec 1913 Pic Rails and none push out more than 1/4" of the rail (which hopefully will prevent any tangling with more direct action oriented furniture).As CGR says, "Not only are CGR products a great way to identify your gun from others, it is also a fun way to express yourself without permanently altering your weapon. Our Patent Pending “Snap and Set” rail clamping technology affords the user maximum placement flexibility, thereby not committing your CGR product to a particular weapon or position..."
Check them out on line at http://shop.customgunrails.com/. They have more than one commemorative 9/11 design and the American flag rail cover is on sale until September 16th. They make custom dog tag pieces as well. If you want to talk to them about a custom rail cover for your tac team, platoon, mall ninja element or even family crest, e-mail them at contactus (at) customgunrails.com. Hat tip to Billy's Custom Gunworks for letting me know about these guys. Note: I was originally going to post these images tomorrow, but decided upon reflection that it might be seen as some attempt on the company's part to exploit the anniversary of 9/11. It's not - they don't even know I'm running this. I do think their 9/11 flag design is particularly inspired. This sort of personalization for someone's rifle seems like an outstanding idea. No, it has no real tactical purpose and it's not a force multiplier of any kind - but it is aesthetically pleasing and gives you a chance to make your weapon just a little more 'your own'. I'll leave it to you to decide if it's worth the money - less than $30 normally, currently less than $20 during the sale.