Synchro (Shinkuro) is a series of cards related to Synchro Monsters. They appear most frequently in the Yu-Gi-Oh! 5Ds anime and manga, although a few also appear in the Yu-Gi-Oh! ARC-V anime.
Most Synchro cards are Spell/Trap Cards that support Synchro Monsters, although there are few exceptions, such as Synchro Boost (which increases the equipped monster’s Level, facilitating a Synchro Summon). There are also a few Synchro monsters, but they are infrequent. (Source : Yugioh Wikia )
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