Apple does not break out figures for how many of each model it sells, but executives pointed to the premium-priced iPhone 7 Plus, which sells for up to $969 fully loaded, as the key to boosting the amount it gets on average for each phone.

The average selling price of iPhones is important to Apple because the smartphone market is maturing and its growth slowing. Apple’s ability to get more cash for each phone sold is critical to growing its profits.

“One of the things that we did not get right was the mix between the iPhone 7 and the iPhone 7 Plus,” Apple Chief Executive Tim Cook told analysts on the company’s earnings conference call on Tuesday, in response to a question about how supply of its top-end phone was constrained during the holiday shopping season.

“The demand was much stronger for the 7 Plus than we had predicted, and so it took us a little while to adjust all the way back through the supply chain and to bring iPhone 7 Plus into balance, which occurred this past quarter.”

The popularity of the iPhone 7 Plus model represents a triumph for Apple with a new departure: packing a unique feature into its most expensive iPhone.

The iPhone 6 Plus differed from its smaller sibling only in screen size, but the 7 Plus model has a physically different camera that enables what Apple calls “portrait mode” for taking shots with a blurred background – a feature more commonly found on large, expensive digital cameras.

It is a strategy Apple could use again. Many analysts believe the company will reserve certain features for the premium-priced model of its next, eagerly awaited iPhone – such as a higher-quality display – that could sell for more than $1,000.

So far, customers seem to be willing to pay more for the extra camera in the iPhone 7 Plus, which is one reason that Apple made slightly more revenue selling slightly fewer iPhones in the latest quarter than a year ago, for an average price of $656.

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That price was 2% higher than 12 months ago, the best improvement in a year. During 2016, selling prices even went into a decline, year on year, during the iPhone 6s cycle after soaring on the release of the original iPhone 6 and 6 Plus, which introduced larger screens to the Apple lineup for the first time.

“The important thing is the average selling price should not fall,” said Anil Doradla, a research analyst with William Blair & Co. “I have full confidence that it won’t. Apple just doesn’t cut pricing to gain market share. It’s not in their DNA.”