Micronized Rubber Powder (MRP) is classified as fine, dry, powdered elastomeric crumb rubber in which a significant proportion of particles are less than 100 µm and free of foreign particulates (metal, fiber, etc.). MRP particle size distributions typically range from 180 µm to 10 µm. Narrower distributions can be achieved depending on the classification technology.

MRP represents an evolution over previous post-manufactured rubber technologies. The most basic rubber processing technology converts end-of-life tire and post-industrial rubber material into rubber chips that are typically one inch or larger in size. These chips are then used in tire-derived fuel and civil engineering projects. A second-generation processing technology converts end-of-life tire and rubber material into crumb rubber, also known as Ground Tire Rubber (GTR). GTR typically comprises chips between one inch and 30 mesh in size, with the associated fiber and steel mostly removed.