About 2"-2.25". Very flexible. I use these for my peyote and brick beading. I also use these for my smallest seeds, they are the smallest I have found. The flexible 12 pack I have listed are a good value for most beading needs, but these are thinner and a better quality.
No. that is the down side, they are difficult to thread. I have used the threader and if you are not careful, the needle will break. I just eyeball thread it now. I also wax my thread, but I always thread, then wax. If I wax first, it just strips the wax off the thread.