Given the range of talents possessed by Sam Whitelock and Brodie Retallick and their durability, the All Blacks can be highly selective about which other locks they include in their squad to play the British & Irish Lions.
Coach Steve Hansen will most likely opt to include four, knowing that the physicality of the series will be intense and the prospect of injury is moderately high.
He'll also want to have a bit of variety up his sleeve - a diverse range of personnel to give the All Blacks a chance to mix things up at various times of the series.
Whitelock and Retallick feature front and centre. They will, as long as they avoid injury, start in all three tests. The other two locks who make the cut, will be picked with a view to how they can support the top combination.
The All Blacks have been willing in the past - the 2015 World Cup - to operate without a specialist lock on the bench.
It's unlikely, though, they will go down that road against the Lions. The visitors have so much power in their pack and are going to be so obviously structured around the set piece and collisions, that the All Blacks will probably be reluctant to risk not having a specialist lock on the bench.
To that end, Scott Barrett is almost certain to be picked in the squad with a view to being the best bench option. He brings a skills portfolio that is broad and as well as winning lineout ball and scrummaging hard, he'll get about the track and contribute.
The fourth place will presumably be kept for a bruising, tight lock, who can add bulk to the scrum, presence to the cleanout and carry the ball hard into the thick traffic.
A few weeks ago, that spot was almost certainly going to go to Luke Romano. It may still end up that way, but possibly coming up fast on the rails is Patrick Tuipulotu.
In 2014, Tuipulotu was one of the fastest rising talents in the country and impressing not only the All Blacks coaching staff, but senior players, too, with his unassuming character and dedication to hard graft.
A natural athlete with an enormous leg drive, Tuipulotu was the go-to-man for the All Blacks in a few big tests that year - coming off the bench in the final quarter to change the momentum with his power close to the fringes.
At 2.02m and 130kg, he's bigger, stronger and more agile than Romano. He's quicker, too. But Romano is using all of his experience and all of his gifts to be playing some good rugby for the Crusaders.
Based on what's been produced so far this year, it's Romano by a length. But there is time yet for the gap to close and for Tuipulotu to force his way into the squad and he took a big step towards that with his 80-minute effort against the Cheetahs on Friday night.
The fact he managed to go for the full 80 after five weeks out with a bulging disc said plenty about his excellent general conditioning and depth of character.
If he had one specific technical goal to fulfil on his comeback game, it was to establish his power: to demonstrate that there are few locks in Super Rugby better at charging close to the ruck and running over the top of defenders.
He managed a handful of damaging runs where he wiped out large segments of the defence and one where he went a full 30 metres for a try. It wasn't conclusive as such, but it was encouraging.
"We are showing we can do the dirt work and I thought the boys numbers one to five provided that platform for the boys out wide to be explosive," said Blues captain James Parsons.
"I thought we rolled our sleeves up in their 22. We worked hard, kept coming round the corner to hit hard and keep hitting and it was great to have Paddy back. I thought he was awesome."
It was a good base for Tuipulotu to say he's finding himself again and ready to build his work back to the high points he knows he can reach.
The Blues have a run of games which will suit him. A bruising affair against the Stormers followed by a local derby against the Chiefs and then a trip to Samoa where the emotional experience for many of the Blues players will be intense.
It's not much time to press his claim, but perhaps it will be enough.