While "Pokémon Gold" and "Silver" retain the basic mechanics of capturing, battling, and evolving introduced in "Pokémon Red" and "Blue", new features were added. A time system was introduced using a real-time internal clock that keeps track of the current time and day of the week. Certain events, including Pokémon appearances, are influenced by this feature. New items were added, with some designed to exploit a new mechanic: Pokémon being able to hold items. A new type of item able to be held was the berry, which comes in varieties and can restore health or cure status effects. Other held items can give boosts to the Pokémon during battle. More specialized Poké Balls were introduced, which make Pokémon catching easier in certain situations. A new item called the Pokégear was introduced, functioning as a watch, map, radio, and phone, allowing the player to call other characters who offer their phone number. Trainers will call for a rematch and others will call about rare Pokémon that can be caught in a certain area.