Marshmello Pack is a Bundle. This cosmetic has been leaked, and the bundle will hopefully be available to purchase in the near future!
How-to Get the Marshmello Pack Bundle
Marshmello Pack was leaked or datamined, which means we don't know for sure how it will be released. Most cosmetics that are leaked will be released within 30 - 60 days of their discovery.
Marshmello Pack's Attachments
Attachments are items that come with a cosmetic when it is obtained.