If you mean the ribbed plastic straps that connect the chest plate to the backplate, the sandtroopers do not have them. Their chest plate and backplate are attached via a strap under the plates. I used 2" nylon for mine.
I knew that they were not ribbed but i thought thet they were abs or styrene. You used nylon fabric? Do you have any pics? I saw the one on your site but I was hoping for a clearer pic. also do you know if the Sandtrooper E-11 had the Hengstler Counter?
At least one of the E-11s did indeed have the Hengstler.
I don't have a pic handy but the chest and backplate butt up against each other and you run a strap on the underside (I used snaps) to connect them. You really can't see the strap at all because the chest and backplate and butted together and also because the strap is black like the undersuit.