Approximately 35% stretch one way and 75% the other will give you flexibility for those days when you need a little bit of leeway (an extra chocolate bar, a layer of longjohns, a long car trip...) without there being too much extra give.
Tubular, so the fabric is 37" wide uncut or 74" wide when cut. I love tubular fabrics; they're so useful. You can make bags, T-shirts, and things like that taking advantage of their tubularness (no, that's not a word, but it should be), or you can cut it open along one of the folds and it's just like any other fabric.
At 6.4 ounces per linear yard, the fabric is 2.8 ounces per square yard.