At one end of the spectrum there is MR6 for hot climates and at the other MR10 for colder ones such as the UK.
The MR6 pellets, which are pink, were named in line with construction terminology, which apparently requires three letters or numbers.
The MR6 pellets made into a piece of plastic are flexible but rigid, unsnappable and with a high-tensile strength.
"MR6 is very good in very hot conditions because it doesn't melt like a traditional bitumen.
"So we use this product out in Turkey, Bahrain and Dubai, and we have just laid a road Australia using MR6, whereas MR10 is used in Scotland, Canada and Russia, where we have very cold conditions."