Info below from the Jerry Harvey website re the issue of foam vs. cotton for blocking the impressions (deep inside your ear). I had impressions done for my JH5s and the audiologist used cotton (I brought the "tip sheet" with me, but they used cotton anyway. Lucky for me, JH turned them around in a single day, which is amazing. Overall time, one week (UPS shipping both ways). Anyway, I also had a bite block (2 in.) while getting the impressions. They fit perfectly first time, every time. Just lucky I guess. I am interested in the 1964 Ears triples, but not sure I want to spend even more (do I need two pair of customs?). So for now, happy with JH5s, which I absolutely adore SQ-wise. Best I have ever heard, by far.
Here's the info from the JH page for audiologists:
3. We also require that the dams are made of cotton instead of foam. Foam will tear the end of the canal when removed for processing.