I ordered both a 4 and a 6 in this style.  Being a first time buyer of NYDJ, I didn't know what size I wear, but I normally wear a 6 in jeans.  Well, other people will back me up on this:  the 4 and 6 are the same size - waist, hips, length, everything.

They are very well made of a medium to heavy weight stretch material that is such a dark blue that it can almost pass for black.  They don't fit as I expected for being called a legging, though.  They fit me more like a loose fitting slim jean.  I'm keeping them anyway because they are so unbelievably comfortable and I'm hoping they will shrink with a hot water wash and dryer.