Upon purchase, you'll receive TWITCH account.
Link it to your game account to claim the following items: 

1. x29 Observer Skins

NOTE: 
!!! Claim items promptly post-purchase; they may expire.
!!! Unlink the Twitch account once all items are collected.
!!! Items hidden after 6 months are still claimable.

These items can only be obtained once per account. When unlinking a Twitch account, items disappear, but when re-linking a Twitch to the same game account, they will reappear.