A constantly refilling pool of talent. Well-rehearsed changeovers. And plenty of speed.
There are many reasons why the Australian women are heavily favoured to win a third-straight gold medal in the 4x100m freestyle relay at the Tokyo Olympics.
None bigger, though, than the trust that they've developed in each other while winning gold at three of the past four Games.
"We've built that through many years of competing together," said Bronte Campbell, who was a member of the 2016 team in Rio and is a "relay-only" swimmer for these Games.
Campbell, a former world champion in the individual 100, might swim only the heats of the 4x100 this year. That's because Emma McKeon, Madison Wilson and Meg Harris all finished ahead of her at the Australian trials last month - as did sister Cate who is swimming in her fourth Olympics.
"It's honestly a real honour and a privilege to be a part of this relay team," Cate said.
"It's been one of the highlights of my career."
The Australians held a 10-day relay camp in February on the Gold Coast, which provided not only a chance for extensive training but also a reunion of sorts amid the pandemic.
"Not everyone lives in the same state and we hadn't seen each other for about a year," Bronte said.
"We really have had no contact with anyone and that's a huge part of it as well, making sure that the team really gels. So that was great."
The team practiced every scenario that they might face in Saturday's heats and Sunday's final - one of the first medal events on the swimming program.
"You have to trust that you've done the work, that I know how to do this and that I can execute it when it matters. And history shows that I can. So it's a lot of preparation and then self-belief on the day," Cate added.
While the Aussies are favoured, the Netherlands also have a veteran team featuring Ranomi Kromowidjojo and Femke Heemskerk, who were both members of the Dutch squad that claimed gold in 2008, when Australia came third.
Sweden, led by 100m world record-holder Sarah Sjostrom, are also a threat, as are the United States - like always.
The key to winning is usually in the changeovers, which require teammates to read each other's strokes.
"The freaky thing about a relay changeover is you actually never see them touch the wall," added Bronte.
"You should be gone and in the air before their hand hits the wall, because your feet should still be on the blocks when their hand hits the wall, which means your body has got to move quite a long time before that. So you just got to pick your mind and then back yourself, because you can't hang around to watch them touch."
In the end, Australia usually touches first.
Australian Associated Press