It's fingering weight - maybe even a little on the heavy side of it. It feels like a wool blend, but I could be wrong.
This is what happens when you swap without labels.
(if you click the picture it takes you to my flickr account where there are more pictures of other, mostly knit related things. If you're bored or whatever.)
Thank you. :)
Edit: Consensus is that this is Bernat Sox, an acrylic/nylon blend (Thank you to all for your help!). So now I have an additional question: How does this feel as a sock? I mean, does it do the things that acrylic do, like not breath? Or does the nylon help to tone that down? Thanks again.