Pirelli has revealed that the teams will run unmarked prototype tyres in both of Friday's practice sessions for the Belgian Grand Prix.

"In FP1 and FP2 we will test prototype unmarked tyres modified to even further protect the tyre from possible consequences generated by accidental multiple impacts on kerbs or other external bodies," said the manufacturer today.

Interestingly, despite changes to some sections of kerbing at a number of previous tracks, there are no such changes at Spa-Francorchamps for this year's race.

Indeed, the only changes for this year's race see the kerb and artificial grass on the exit of Turn 7 extended as far as the end of the gravel trap and the artificial grass behind the kerb on the exit of Turn 15 extended back towards the corner as far as the green painted section of asphalt.

Last year, Sebastian Vettel suffered a high-speed failure exiting Eau Rouge which was subsequently found to be due to debris after the German ran wide, the Ferrari driver suffering a similar issue in Austria this year. Prior to Vettel's failure at Spa, Nico Rosberg suffered a similar high-speed failure during Friday practice.

It's understood that two sets of tyres will be available for each driver for evaluation on Friday.

Check out our Thursday gallery from Spa, here.