This is a 25 character Xbox code which unlocks the Assassin emblem to be used in-game with Halo 4 on the Xbox 360 (also available to play on Xbox One).

Code needs to be redeemed on an Xbox and will be sent via eBay message.

It was available via pre-ordering the game and is unavailable to purchase from the Xbox 360 marketplace.

As these are single-use codes I'm afraid I cannot accept returns.