usually the largest and heaviest players on a team. In attack, their size and strength means that they are primarily used for running directly into the defensive line, as a kind of "battering ram" to simply gain metres. Similarly, props are relied upon to defend against such running from the opposition's forwards. Prop forwards that feature in their respective nations' rugby league halls of fame are Australia's Arthur Beetson, Duncan Hall, Frank Burge and Herb Steinohrt and New Zealand's Cliff Johnson. Back row Three forwards make up the back row of the scrum: two second-rowers and a loose forward. All three may be referred to as back-rowers. Second-row forward Second-row forwards are numbered 11 and 12. While their responsibilities are similar in many ways to the props, these players typically possess more speed and agility and take up a wider position in attack and defence. Often each second rower will cover a specific side of the field, working in unison with their respective centre and winger. Second rowers are often relied upon to perform large numbers of tackles in defence. Second-row forwards that feature in their nations' halls of fame include New Zealand's Mark Graham, Australia's Norm Provan, George Treweek and Harry Bath, France's Jean Galia, and Great Britain & England's Martin Hodgson. Loose forward / Lock forward Numbered 13, the loose forward or lock forward packs behind the two-second-rows in the scrum. Some teams choose to simply deploy a third prop in the loose forward position, while other teams use a more skilful player as an additional playmaker. Loose forwards that feature in their nation's Halls of Fame include Australia's Ron Coote, Johnny Raper, Bradley Clyde and Wally Prigg, Great Britain's Vince Karalius, Ellery Hanley and 'Rocky' Turner, and New Zealand's Charlie Seeling. Interchange In addition to the thirteen on-field players, there are a maximum of five substitute players who start the game on their team's bench. Usually, they will be numbered 14, 15, 16, 17 and 18. Each player normally keeps their number for the whole game, regardless of which position they play in. That is, if player number 14 replaces the fullback, they will wear the number 14 for the whole game, and not change shirts to display the number 1. The rules governing if and when a replacement can be used have varied over the history of the game; currently they can be used for any