According to MacRumors, SVP Craig Federighi personally responded to an email from a developer and product designer named Keith Krimbel. Krimbel shared his email, in which he asked whether Face ID would work with sunglasses and what would happen if a thief grabbed his phone, pointed it at his face then ran, on Twitter, as well as Federighi’s reply.

In his reply, Federighi said that Face ID would work with “most, but not all” sunglasses. “Most sunglasses let through enough IR light that Face ID can see your eyes even when the glasses appear to be opaque. It’s really amazing!” he added.

E-mailed #CraigFederighi about #FaceID and actually got a response! pic.twitter.com/3Ytt1k6WvK

— Keith Krimbel (@KeithKrimbel) September 14, 2017

In response to Krimbel’s question about crime prevention, Federighi said there are two ways to stop a thief grabbing the phone as well as gaining access to it.

“If you don’t stare at the phone, it won’t unlock,” he wrote. “Also, if you grip the buttons on both sides of the phone when [you] hand it over, it will temporarily disable Face ID.”

Many questions have been raised over Face ID, including whether an identical twin would be able to hack their sibling’s phone. Apple claims the software can only be duped one out of 1 million tries (versus one in 50,000 tries using the fingerprint sensor).