R131 "NEXT"- Hightech Material Ballistic strap, water resistant with a cream white stitching. When you purchase a RIOS1931 watch strap you are acquiring a high quality craft product. The combination of traditional , handcrafted perfection while constantly evolving has made the watch straps of RIOS1931 a unique, top quality product. R131 "NEXT" watch straps are available from 18 to 22mm, in black only. Thickness of strap: (aprox) 6.0 mm to 3.0 mm. Cross Section: round. Select the size and colour that best suits your needs. Lug/Buckle Measurements: 18/16mm, 20/18mm, 22/18mm.