Celebration Hat is one of the three premium skins released as part of a 4th of July 2017 offer. It was available for individual purchase in late June to early July 2017.
Celebration Hat could be purchased for 1990 coins in the Skins Shop under the “Independence” or “Independence Day” tab. This skin may not be available for purchase in the future.
Details of this offer may vary depending on location and platform.