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

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. You will only receive items that you have not received before. To receive items, you must unlink the old twitch from your game account.