As far as I know, the balanced acupuncture method created by the Acupuncture Teaching and Research Office of Hunan University of Traditional Chinese Medicine uses ordinary acupuncture needles commonly available on the market. This needle follows the "steel needle" used in previous acupuncture. "The title, in fact, is mostly made of alloy, which does not rust, fade, or break easily. It is not much different from steel needles in use, but is thinner and more flexible. It can be regarded as a change brought by the advancement of manufacturing technology to acupuncture.
I have seen the kind you mentioned in the acupuncture teaching and research office, and there are still several copies on the table. It was not a special needle, but an old version of acupuncture needles, both Universal and Huatuo brand. The packaging was a two-sided hard plastic case, each containing ten needles. Huatuo's brand is plastic-paper packaging, and Global's is plastic-tinfoil packaging. The packaging indicates that the diameter is 0.4mm, which is indeed much thicker than current acupuncture needles. The needle body is thick, the needle hole is large, the breath is strong, and it feels hard when held in the hand. This kind of needle is just because the material technology was not developed in the past. It is not a special needle and it is indeed not available on the market. Furthermore, I have never seen anyone using special needles when using balanced stitches.