Ok that makes no sense
It is Tenebrex (TA66). I have one on my TA31RCO-M4. Works fine as an objective lens protector.
Scopecoat (TA63) is even better. I don't think flip ups work on an ACOG. Your 3.5x is meant to be shot both eyes open for maximum situation awareness. Flip caps are distracting.
Scopecoat is cheap. Killflash not so much. I have read that they (killflash for your model) don't stay on well (mine screw on).
You own the world's best eyes open optic, IMO. Just get a scope coat.
My 2c...
That makes no sense to say oh they don't make lens caps for the TA11 3.5X35 ACOG scopes because lens caps are distracting and pretty much defeats the purpose of the two eye open shooting with the Bindon Aiming Concept models, think about it, as far as I know pretty much all of the 4x32 ACOG scopes have the BAC feature especially the RCO models and they make the killflash and scope cap combination for all of those models, the BAC is a main feature on Trijicon scopes so saying the lens caps would draw your attention instead of the targe is rediculous???? I've owned several ACOG scopes and red dot sights, I own two ACOG's right now, a TA11H-G with RMR that has green triangle and I also have a TA31RCOA4 so with that way of thinking you could say the RMR on top of the scope would draw your eye away from the lense, or the leash/lanyard on the adjuster caps or the TA51's knob mounts or any other number of things would draw your eyes away???? So no way that lens caps, adjuster leash, RMR, or any other part or piece is going to defeat the BAC feature because anybody who's ever used an ACOG with the Bindon Aiming Concept can tell you that lens covers aren't going to draw your eyes away from looking through the scope with your scope eye and the un magnified target with your off scope eye..
What makes the BAC= Bindon Aiming Concept work is that the center illuminated part of the reticle draws your scope eye to that part and makes the image appear to float over the object on your off scope eye, that's why the full line illuminated versions cannot work with the BAC, it's because the entire reticle is illuminated red (or at least 95% of it is illuminated, where with other models it's just the center aiming points that are illuminated)so anyway the small illuminated part of the reticle is what allows the shooter to focus on the target with their off scope eye while sub consciously overlaying the illuminated reticle onto your target. The only problem with this feature is that it doesn't always work the way the shooter naturally looks through a scope, what I mean is, I am a left handed shooter so my left eye is my natural scope eye so if it is my strong or dominant eye then the BAC will work for me, however if my right eye were my dominant eye then the BAC won't work for me unless I either spend a lot of time adapting or training my left eye to to be my dominant eye to work better with the BAC or I would have to start learning shoot right handed so that I could learn to use the two eyes open BAC. Trijicon even explains this in some detail in their manuals for BAC scope models, luckily for me my left eye is my dominant eye because it would be more trouble for me to learn to shoot right handed and use a dominant right eye then I care to worry about.
The way they describe how to tell which is your dominant eye is to look through the scope with your natural scope eye while trying to focus on the target with your off scope eye and if you can see the center illuminated part of the reticle overlaid on the target with the non magnified image then your good to go, but if you can't see it then you try to use your normally off scope eye to look through the scope and try to focus on the target with your normal scope eye and if it works then you have to either consciously train your non dominant scope eye to work with the BAC or learn to shoot from your other side be it either left or right...
So no it has nothing to do with the scope caps drawing your attention away from the target, it's just that Trijicon is plain to lazy to go through the trouble to make the accessories for the TA11 series, however if you go to their website and browse through their scope models and take a look at the TA11MGO (MGO= Machine Gun Optic) and that model TA11 does have scope caps for it, and it has to have the killflash mounted for the front lens cover to fit on the scope, but the front of the MGO version doesn't have the typical ACOG angled front housing so the killflash and front lens cap won't work on a standard TA11, but the rear eyepiece lens cover should fit the standard TA11 models and yet they still don't make at least the eye piece lens cover available, but they could if they wanted to, they could also make a killflash that fit and stayed mounted properly if they wanted to do that too but they don't seem to care as much about the 3.5x35 ACOG's as they do the 4x32 models. I really don't know their reasoning behind it? Maybe they don't sell enough of the 3.5x35 models as they do the TA31 series scopes to make it financially beneficial to their bottom line? Whatever the reason they don't do it is kind of messed up for those of us who want to protect our very expensive ACOG's just as much as owners of the 4x32 scopes want to, so we should have the same accessories available for our scopes as any other scope owner, especially when you considder the prices keep going up, when I bought mine the Trijicon MSRP was $1150.00 and then the prices went up to $1325, and now they are selling for something like $1595.00 for the exact same scope I paid $1150.00 for only a couple years ago and still they aren't making the same accessories for my scope as they make for other models and that's kind of messed up in my opinion. Like I said I own a TA11H-G M249 reticle which inside scope bottom is labeled 3.5xM29 which means it's the dual illuminated green Horseshoe Dot M249 1000 meter ranging reticle M249 means it has the same reticle pattern as the TA11MGO for the MG249 squad machine gun so why can't I have the same lense cap for my scope? My TA31RCO has scope caps and killflash on it and the killflash fits and stays where it's supposed to, but the TA11 killflash actually sucks Anyway sorry to rant and get off topic, but the point remains that the 3.5x35 ACOG's should have the availability of killflash and scope caps that stay put and fit right just as the other ACOG's have for them and NO WAY will scope caps draw your attention away from looking at the target through the scope or with your off scope eye and it's rediculous to even try to say they will
Sandman