These are Trekking Pro Natura, the new bamboo blend. I really like the texture and look of the yarn:
The only issue I had was that it had tufts of what I'm guessing is the bamboo bit that weren't fully twisted into the yarn in spots:
Which obviously isn't thrilling. (That was the worst spot in the whole skein; there were one or two other similar, but lesser tufts.) But I'll still buy and use the yarn again.