Winter Boxes contain two lots of Incense, two Incubators and five Star Pieces. Great Boxes contain four Super Incubators, ten Razzberries and ten Star Pieces.
Ultra Boxes, meanwhile, contain a whopping 25 Star Pieces, as well as eight Super Incubators, ten Pinap Berries and ten Lure Modules.
Star Pieces are particularly useful, because they grant users double stardust from all situations for 30 minutes.
“In addition to more Ice-type Pokemon appearing around the world, additional Water-type and Ice-type Pokemon originally discovered in the Hoenn region in the Pokemon Ruby and Pokemon Sapphire video games will also begin appearing in Pokemon GO for the very first time.”
The event also features free single use Egg Incubators, which are rewarded for the first PokeStop visit of the day.
The only downside is that the free Incubators are only available until Christmas Day.
Niantic has also announced a surprise festive bonus as part of the Pokemon Go Christmas event.
In order to give players a better chance of catching more Gen 3 Pokemon, Niantic has made a major change to Lure modules.
Instead of lasting just 30 minutes, Lure Modules will last for six hours.
The effect will last until January 4, which is when the Christmas event comes to an end.
“Surprise, Trainers! In celebration of the holidays, from now till January 4, Lure Modules will last 6 hours when activated!” Niantic confirmed.