elastic workout band

anyone know a good site to buy one of these ??

looking for what's basically a giant rubber band - not the elastic rubber tubing with the handles on the end

about an inch wide, 2 mm thick, and 4 or 5 feet when folded in half (meaning it's 8 to 10 feet long)

i've used one before for stretching, but can't seem to find it.

or if anyone knows where you can get the stretch thread thing - basically looks like thread (well, not thread, but almost seat-belt like material) with a bunch of semi-circles on it, the entire length - so you can stick your foot in it.