Formula 1 tyre supplier Pirelli has announced the tyre compounds which will be available to Formula 1 teams at next year's Australian Grand Prix.
The event, which will take place from March 18 to 20, will act as the first under new regulations, which sees each driver select compounds from the range of five.
The Ultra Soft tyre has been added to the 2011-15 range of Super Soft, Soft, Medium and Hard.
"Pirelli will bring the following three compounds to the opening round of the 2016 Formula One season in Australia: Medium, Soft, Super Soft," read a statement.
"These are the tyres that Pirelli has said must be used at some point in the race: one set of Medium, one set of Soft.
"Each driver must have both these sets available for the race, and must use at least one of them.
"There are the tyres assigned for Q3 in qualifying: one set of Super Soft.
"Following on from the 2016 regulations, each driver must save one set of the softest of the three nominated compounds for Q3.
"This set will be given back to Pirelli after Q3 for those who qualify in the top 10, but the remaining drivers will keep it for the race – as is the case currently.
"The teams are free to choose the remaining sets; making up 13 sets in total for the weekend."