What is the red striped sticker for?

i wondered what it was for too. Brought it with me to FedEx where the customer in front of me (shipping a phone as well) had it stuck around the corner of the box. Security tape she said. Made sense to me so I did the same!

We are just users like you and have no special insight into why Apple does what they do. For all we know that could be the backing of a shipping label that was put into the box instead of being discarded.

If your mailing instructions don’t mention what to do with it then don’t worry about it.

Support does not know but I figure it is "tape" to seal the box. I received two kits for two different iPhones and both have a sticker inside but one is clear. For the X phones they have switched to this red stripe and the directioons are genrally lacking. The other instructions say seal the box with the included sticker.

It's tamper evident tape used to seal boxes.

The marking shows clearly if the tape was cut or peeled off and taped back down.

I believe that is to indicated that the box contains a device with a lithium battery.

Not helpful. You are saying “i guess”

its ridiculous for apple to insert a stupid sticker with no instructions

I got one too. I’m guessing to re-seal the box.