Textiles can only be called bamboo if they are made directly from actual bamboo fiber. Textiles made from rayon (or viscose, which is the same thing) that was created using bamboo as a plant source may be labeled and advertised as “rayon (or viscose) made from bamboo.
I have these. They’re very not bad. Not quite filled enough to be perfect. But reasonably firm and reasonably comfortable. They’re better than a rolled up towel, but not as good as the travel pillow I bought at Brookstone circa 1998.
If you’re serious about your travel pillow, this buckwheat pillow is the absolute best one around. I still mourn the loss of mine on a flight out of JFK. I don’t fly as much since, so I haven’t needed a replacement.