Apple did something very uncharacteristic with the launch of the iPhone 6s and iPhone 6s Plus – it made the devices both thicker and heavier than their predecessors. While many people attributed this weight gain to the new 7000 series aluminum the new iPhones use. It appears, however, that the weight gain is actually attributable to the new 3D Touch display.

According to figures revealed in the official environmental documents for the new iPhone 6s and iPhone 6s Plus, the new display assembly weighs twice as much as the display assembly used in last year’s iPhone models. In the iPhone 6, the display assembly weighed 12 grams. In the iPhone 6s, the display assembly weighs 29 grams, more than double the weight of last year’s model. When you think about all of the technology that goes into 3D Touch, it makes perfect sense for there to be a considerable weight gain. Apple had to add an entire new layer to the display to measure pressure, as well as a new capacitive pressure sensor to the backlight of the display.

Overall, however, this year’s iPhone 6s and 6s Plus weigh 14 grams and 20 grams more than their predecessors, respectively. The switch to 7000 series alloy aluminum accounts for just 2 grams of the weight increase of the iPhone 6s Plus, while the iPhone 6s’s aluminum actually weighs a gram less.

The weight and thickness increase of the iPhone 6 and especially the iPhone 6s Plus will lend to a more sturdy design and likely cease all the complaints of phones that bent when put under pressure.