At the moment I'm using a 3.5 mm needle to knit the Swallowtail Shawl (in the same color and with the same yarn as the original - how original of me, eh? :D Give a gal a break sometimes. :p I'm doing enough projects where I substitute yarn and then have to recalculate everything. I guess, that's the reason why I like doing scarfs, they are quick to knit, nobody cares about gauge or swatches, and you don't have to worry about the right fit, which can become something that a perfectionist likes to obsess about - frogging, reknitting, frogging, reknitting. Ugh. Just give me the original yarn... :D ). Anyway, for knitting with the Misti Alpaca yarn they are good solution, as this yarn is so slippery (but also oh-so-soft, I'm in love with it. :D ), but with the wood needles there is a tad more friction to keep them on the needles.
Here's another close-up. "Holz & Stein" means wood and stone.
They are actually perfect. There is just one thing that bothers me a bit, I knit a bit tighter than other people it seems and when I do the row with the decreases and yarnovers and change to the purl row my stitches get a bit stuck at the join and I have to move them manually. With my other needles (Inox) I had less problems as the needles had a smaller diameter around the join and then gradually increased in size.
Add: My mom bought the needles in a department stores, but you can also order the needles at the manufacturer's, Holz & Stein, website.