This site has the largest collection of photographic backgrounds in different solid colours, shapes, sizes, fabrics, utility and
refractive index.
https://www.backdropsource.co.uk/collections/photography-backdrops
The Audio Of the Online Shop which have 250 plus products of studio equipments and backdrops.
Muslin backdrop fabric is made of 100% cotton yarn with impeccable finish, sewn on all sides, lint free.