Encoder belt

 
 Does anyone have a source for a belt like the one pictured?  

I think I have seen them in catalogues, but wasn't getting anywhere searching.

Then I tried a Google images search and I think it might be a variant of the Berg Flex-E-Belt.
www.wmberg.com/products/belts-and-chains/flex-e-belt

I'm glad you were having a hard time also. I searched for a couple days before I finally decided someone here has seen these before. I had no idea what to really search for honestly.

Thanks for the link, I'm pretty sure if I can figure out the sizing these will work