Apple may have surprised us with several innovations this year, the latest of which being their iPad Air2. The tech giant says that its new tablet still gets the same 10-hour usage time as last year’s iPad Air, despite the 15 percent smaller battery incorporated in the device.

Granted, we could have seen that one coming since the iPad Air 2 is 18 percent thinner than its predecessor, too. What isn’t yet clear is how Apple ensures the same battery life when providing less juice to do it with.

According to Apple statements, a new innovation, the A8X chip, combined with software improvements allow the iPad to make up for the difference in battery size.

“Usually, increased performance comes at the expense of battery life. Notice we said ‘usually,'”

the tech giant said in one of its marketing materials.

Apple’s iPad is considered the No.1 tablet in all battery life tests, and for the most part, Apple has continued to make great leaps every year to ensure that no one else gets their hands on the coveted No.1. spot. Since being released, the iPad has been lauded not just for hardware design but also for it’s longevity.

Several reviews, including that of Scott Stein, confirmed Apple’s claims, saying that the battery holds up to marketing statements.

“The iPad Air 2 is a nice refinement and finesse of last year’s model, with a bevy of tweaks, enhancements, a much faster processor, and the welcome addition of Touch ID. Simply put: it’s still the gold standard for tablets.[…] battery life remains the same, although its battery life is already pretty good.”

he said in a recent review.

However, despite Apple’s claims, there are some who aren’t convinced. Walt Mossberg, for instance, from Recode, found that the original iPad Air did much better in the department:

“In fact, in one key metric, battery life, the Air 2 actually regressed from the original Air. In my tough battery test, it lasted 10 hours and 37 minutes, exceeding Apple’s 10-hour claim. That’s quite good, better than most other tablets. But in 2013, the original iPad Air turned in the best tablet battery life I’ve ever seen on my test: 12 hours and 13 minutes — about 90 minutes longer.”

The tech giant did not immediately respond to requests asking for comments or future information on whether the smaller battery incorporated in its new iPad Air2 could result in a drop in battery life when compared to its predecessor.