Also on the track are jammers with one from each team who are the point scorers.
It is the jammers' role to attempt to break through the pack and score points for each opposition player they pass.
Following an extensive set of rules modern roller derby also includes a large group of officials who keep the players in line and track game statistics.
There are up to seven referees required during a game, each with individual responsibilities.
Up to fourteen non-skating officials are also required and generally include newer skaters or in Steam Roller terminology "groupies".
The Steam Rollers welcome spectators to dress in their rock star best for the event, with prizes being given to the best dressed adult and child. The teams also ask their friends, family and fans bring a sign to show who they're supporting.
The best supporter sign will win a signed, framed copy of the event poster and Sulphur City merchandise.
Half-time entertainment includes the annual Slam Rock Air Guitar Competition which invites adults and kids from the crowd to compete in an air guitar battle in the centre of the track.
"The Steam Rollers really pride ourselves on our Slam Rock event," said Motley Crew co-captain, Nat Calder, a.k.a Nat Demon.
"It's by far the biggest fundraising event we do each year and funds raised are put toward the cost of our travel games, uniforms and skate gear for our new recruits.
"With the help of Layla's company, WildSide Promotions, a lot of effort goes into the event from concept to promotion to execution and our volunteer crew are well looked after and the feedback we get from those who have attended is always outstanding," she said.
Slam Rock has sold out in the past three years, so ensure you purchase your tickets when they go on sale to prevent disappointment.
Door sales are not guaranteed.
Tickets for Slam Rock go on sale at 9am on June 1 from Ticketmaster at the Howard Morrison Performing Arts Centre or online at www.ticketmaster.co.nz.
More information about Slam Rock 2017 can be found at www.facebook.com/events/1891253701116720/.