This strap appeared to be blue denim - until I opened the pack !
The fabric appears to be extremely fine like polyester, but with a vivid white base to the pale blue top colour.
I then noticed a stitched on label to one of the leather ends. It states:
When it gets wet, the color may change, or product color may be migrated to your clothing.
So - Don't stand out in the rain ! - You may get the "(Pale) Blues", or even a "Whiter shade of".
The main strap has a fine brown backing fabric and there appears to be some brown cellular foam padding (rather like a trainer insole) between the backing and the outer coloured fabric.