Blitzkrieg Betties’ jammer (green), identified by the star on the side of her helmet, pushes her way through the opposing team members from the Machine Gun Mollies at the gymnasium here Sept. 24. There is one jammer per team; they score points for each lap completed. The Devil Dog Derby Dames roller derby league, which is made up of status of forces agreement personnel and service members, contended against each other to keep their competitive edge.