Material: nylon that has had the seatbelt like weave, 2 layers glued and stitched together, so it is 2.9 mm thick. Edges and holes are laser-sealed so all should be smooth. Hardware is kept in place by stitching. End points of the stitches can be melted and pressed flat with a small flame.
The buckle is attached with a push pin, so you can replace it with a buckle of your watch-brand.
Buckle and loops are 316L steel, with a brushed finish.