Technically Specified Rubber

Technically Specified Natural Rubber(TSR) or ISNR as is named in India is a commodity with standard specifications can be divided into six main standard types - ISNR 3CV, ISNR 3L, ISNR 5, ISNR 10, ISNR 20 and ISNR 50. Tire manufacture is their primary application.
TSR are rated based on a number of variables, such as the amount of dirt, ash, volatile matter, color, viscosity, and/or chemical components such steric acid and carbon black.
With regards to the international ISO standard, each major producing nation sets its own TSR standard. For example, Thailand uses the symbol STR (Standard Thai Rubber), Indonesia uses SIR (Standard Indonesia Rubber), and Malaysia uses SMR (Standard Malaysia Rubber).