They're resin--a high-quality plastic, lightweight but with a nice solid feel. They are less slippery than metal but not as grabby as wood or bamboo. In fact, they are good, useful middle-of-the road needles.
The tip sizes run from US 5 to US 15, with larger sizes available.
The spot where the tips join the cable is impeccable -- easy to operate and I've never had one come loose.
The cords are a bit thick for some people's taste and the points a bit blunt.
They come in a compact, well-organized box -- great for having many sizes with you when you travel.
I'd buy them, but I already have two sets.....