I have no idea what sizes my needles are, but I can tell the JJ needles from the other ones.  No, I'm not kidding--these are so much smoother, even when hand-sewing multiple layers or tightly-woven fabrics.  Unfortunately, my other needles aren't that old or I'd just get rid of them all and replace them.  Do check types and gauges to make sure you get what you need for the type of work you're doing, but in general I'm always very pleased with the quality of these.