IL-Cornfed is right. Usually 3D Carbons are striaghter around +/- .001 when most good carbons are +/- .003 and cheap carbons are +/- .006. I use them (Carbon Express 3D Select 300's) and have never broken one, and every deer I've shot with them is still in my quiver. They're still tough! One not: 3D arrows are usually fairly lite, if you like a heavy arrow you might not be able to find one.

Good Luck!