Apple’s newly launched battery cases for the iPhone XS and XS Max have more battery capacity than any of Apple’s prior cases. The Verge initially reported that the cases’ battery capacity was the smallest yet, but that information was incorrect.

Strictly speaking, the new Apple cases have the lowest mAh rating, at 1,369mAh. But that’s because instead of using a single large cell (like the iPhone 7 battery case’s 2,365mAh battery or the iPhone 6 case’s 1,877mAh), Apple is using two battery cells wired in series, which keeps the net amperage the same but lets it boost the voltage to 8.7V, dramatically higher than the estimated 3.8V that the older cases output power at.

Because of that difference in voltage, it’s better to look at the total power output in Wh (1 Watt = 1 Volt x 1 Amp) for directly comparing the three Apple cases: 10.1 Wh on the new case, compared to 7.13 Wh on the original iPhone 6 model, and 8.98 Wh on the iPhone 7 version. (For a more detailed breakdown as to why this is a better metric for comparing batteries, check out The Wirecutter’s guide here.) So, at the end of the day, the new cases should supply more power than the old ones did, and do it more efficiently.

We still don’t know the battery capacity of the iPhone XR case, but Apple’s battery life estimates suggest it’ll be similar to the XS and XS Max. Apple is claiming up to 75 percent extra usage time for these new battery cases, although we have yet to test those claims. These new battery cases feature physically bigger humps than the previous ones, perhaps due to the extra room needed for wireless charging.

All three cases cost $129 and come in black or white.

Both iPhone XS and XS MAX Smart Battery Case have a 1369 mAh capacity. iPhone 7 version was 2365, iPhone 6 was 1877. pic.twitter.com/MtJdFC98qQ — Nick Guy (@thenickguy) January 16, 2019

Correction January 16th, 5:00PM ET: Apple’s new battery cases supply more power than previous ones. This article originally stated that the battery capacities were smaller, which is not entirely correct based on how the cases are designed. We regret the error.