Roller derby

I went to watch some roller derby today, it was a Halloween Charity Brawl and my friend was skating in one of the teams. It's still not a very popular sport but there's a UK league and some extra events like today to make it more familiar to everyone. In short, there's two teams of 5 people skating around the track, one of each team is a jammer, trying to get past 4 blockers of the opposite team and score points. The girls on the photo are getting ready to block opposite team's jammer.