Thank you for your response, they state that their unique weave makes them different from other stretchy wraps stating:
The JPMBB wrap is the only one that stretches in every direction: vertically, horizontally and diagonally. This makes Pocket Wrap Cross Carry more flexible than with other fabrics. Even if there are several layers of fabric in this carry, Baby is held evenly with a harmonious tension, while the lower layers of fabric keep their stretch.
Woven, 100% cotton wraps (cross twill) can only stretch a bit diagonally. They are soft and firm at the same time, that's optimum for Baby's and wrapper's comfort in Kangaroo Carries, where there's only one layer of fabric on Baby's back.
Knit, 100% cotton wraps that only stretch lengthwise aren't ideal for Cradle Carries that need the fabric to stretch widthwise. This uneven stretch, and the fact that they are often quite narrow, makes them harder to use with a bigger Baby.
The fact that the stretch comes from the weaving and not the fiber can lead to sagging when the wrap is used frequently with a heavier child.
Even though the moby has 5% spandex apparently it doesn't hold the same elasticity so eventually stretches and sags!
You can get them from UK suppliers and we actually have a baby shop in Northern Ireland thays supply. I guess they aren't that we'll known.