I was hoping that there was a way to purchase more of the large inserts without buying the entire Tank Tread Upgrade kit. $30 is quite a lot for 10 large inserts (we have plenty of the other parts).
We appreciate you taking the time to submit this product idea. At the current time there is no plan to release these flaps individually, but we’ll keep this in mind for a future release.
For every product release, we need to make sure the item makes business sense for release.
John V-Neun talked about that briefly in a post here:
https://vexforum.com/showpost.php?p=312370&postcount=10
Do you find yourself using just the large flaps more than the others?
Personnally this year we ran out of large flaps and had too many small flaps
Agreed. The large flaps get used a whole lot more than any other size, and we need a lot more than the other sizes as well.
I wonder if there would be interest in aftermarket flaps cast out of polyurethane to be functionally identical to the VEX flaps. It sounds like this is a common problem. It’s not exactly a difficult shape to fabricate.
The big inserts are pretty much all we have ever used
My school has also wanted to buy the big flaps by themselves.
Thank makes sense. Thanks for the quick answer.
My students tend to use the large flaps much more often (for intakes especially). We use the medium flaps as well, but very rarely do we use the smaller. Though that could change with some of the designs I have seen for Skyrise.
It seems anyone I ever see using the flaps are using the larger flaps way more frequently then the smaller ones. This reminds me of a similar product where anyone who uses the linear motion kit almost always use the inner sliding blocks over the larger ones. I know I personally have about 40 of the outer blocks just sitting around because there never seems to be an advantage of using them over the inner ones.
-Nick
I doubt you’ll be able to get them completely identical to vex products. Minor differences in a part like this would have a big impact…
We have always used a lot more large flaps, and sometimes medium flaps, occasionally the rubber tread grips for demo tank bots but we have never once used the small flaps 
I agree with others. When my team decides on a flap setup, we really only need one type (a bunch of small ones or a bunch of medium ones, or a bunch of the large ones).
http://www.vexrobotics.com/catalog/product/gallery/id/281/image/12760/
The third flap barely gets used I’ve think I have only seen it used effectively on 323Z’s
Sack Attack Robot.
Our team also uses mainly the large flaps, the reason being, when we want something like a flap its because we need something that can bend and move to the object but remain stiff after contact. the tiny flaps dont have much bending room, and remain stiff most of the time. If I needed something that small, I would most likly use a rubber link or a small standoff.