Following reports that the new iPhone 6 Plus has been getting bendy — and not in a good way — Apple has actually gone so far as pulling back the curtain on its top-secret testing lab, as part of an effort to demonstrate the rigorous tests it puts its products through.

It’s not a new PR strategy for Apple: The company allowed select journalists into its labs following the “antenna gate” drama of 2010, when the new iPhone 4 was found to lose reception when users touched a certain part of the phone.

In this case, Phil Schiller, Apple’s vice president of worldwide marketing, repeated the statement the company released earlier today about bent phones: Apple has received only nine reports of bent iPhone 6 Pluses, a tiny percentage of total units sold. He recited a laundry list of components that go into the iPhones, including their unibody construction, high-grade aluminum, the “strongest glass in the industry” and stainless steel and titanium inserts.

What the company hasn’t said previously is that about 15,000 iPhone 6 and iPhone 6 Plus review units (each) were put through an “exhaustive” testing process before launch — the most testing the company has ever done, it says. The majority of this testing occurs in China, but many units are also put through the wringer here in Cupertino, Calif.

Dozens of engineers of varying sizes and weight are seeded with mock-up or dummy units in the months leading up to a new phone launch. Those engineers report back their experiences, and the lab test specifications are tweaked based on those reports.

I saw four tests performed in Apple’s labs, just a few blocks away from the main building of its sprawling Cupertino campus. I’ve outlined them below. These are just a few steps the company says it takes; the short tour didn’t include tests around display strength, water-resistance or other wear and tear benchmarks.

In full disclosure, I have never been to the labs of other companies in the smartphone market, so I can’t say whether what we saw today is on par with other manufacturing tests. I did, however, try to pick up a stack of 25-kilogram weights (about 55 pounds) at one point and was unable to do so; Apple then applied that weight to an iPhone 6 Plus, and it emerged externally unscathed.

Sit Test

First was the “sit test.” This is where, as you might have already guessed, Apple tries to replicate what it’s like when your butt-meets-seat.

Dan Riccio, Apple’s senior vice president of hardware engineering, says this test is the one that is most relevant for customers with concerns about the phones bending in pockets. There are three parts to the sit test. The first part simulates a typical user sitting down on a hard surface, the second simulates someone sinking into something softer like a couch, and finally there’s what Riccio calls a “worst-case” tests, where someone would have a phone in their pocket and sit down on a hard surface at an angle.

Riccio says the company cycles through these, “thousands of times.”

The Three-Point Bend Test

This test is probably “more relevant to the videos you’ve been seeing,” Riccio said. Up to 25 kilograms of weight is pressed across the center of the phone (front and back), which is less than the weight the phone can actually tolerate. In the test below, the smartphone did bend under the weight; but when the metal bar was released, the phone looked like it breathed back into shape.

I asked Riccio why these phones appeared to reset themselves when customers are reporting that theirs remain bent. He said it’s because in certain cases, if users apply a huge load beyond a natural point of deformation, the phone can “take a set.”

The Pressure Point Test

No, this is not some psychological test administered to Apple’s PR people just before they join the company, or just after a faulty launch. In this test, a firm pressure point of 10 kilograms in weight is applied directly to the center of the phone.

The Torsion Test

Finally, there was the torsion test, where we saw an iPhone 6, an iPhone 6 Plus and a MacBook Pro being twisted from both ends at various angles. Apple wouldn’t say to which degree the products are twisted.

That was all that was demonstrated, although again, Apple says there are many more tests performed.

Since the iPhone 6 and 6 Plus are put through exactly the same tests, despite their differences in size, I asked Schiller whether any complaints had been filed about the iPhone 6 bending.

He avoided answering directly, replying that the company receives complaints around all of its products at some point, but that they’re extremely rare.

Check out the video below for an inside look: