According to the retail giant, Walmart added virtual reality training into 30 of its training centers to help employees experience a real store environment, and teach them how to handle situations like massive crowds and long lines on Black Friday. All of this education can take place without having to disrupt an actual Walmart store and its customers.

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For example, a new Walmart store manager may have never experienced a Black Friday. The VR experience could show the employee how crowded a store will get and to which areas shoppers flock.

Tech news site the Verge reported that Walmart’s VR training is actually powered by startup Strivr.

“We’re using computer vision to map scenes, so we literally know exactly where someone’s looking,” Strivr CEO Derek Belch told the Verge. “If they don’t look at [the right place] and press the button indicating that they have seen the stimuli that we’re looking for, we know.” That simulation is particularly helpful in knowing if an employee understands the exact layout of a store and where merchandise is placed.

One of the major challenges in this scenario is that the headsets Walmart are implementing, such as the Oculus Rift, can be costly, limiting how many headsets Walmart can have in a training center.

But Walmart says the results from VR training are “promising,” and will now be rolling VR training out to all of its 200 training facilities by the end of 2017.