From Yu-Gi-Oh!

Synchrons are a series of Tuner monsters used by Yusei Fudo and Sherry.

Most "Synchron" monsters have a corresponding "Warrior" Synchro Monster that requires it be used in the Synchro Summon and their levels go from 1 to 4 in this order: Turbo Synchron (Level 1), Nitro Synchron (Level 2), Junk Synchron and Drill Synchron (Level 3), Road Synchron (Level 4). The Synchrons who do not have Warrior counterparts, (Fleur Synchron, Hyper Synchron and Quickdraw Synchron) are Levels 2, 4 and 5, respectively. Also, every Synchron apart from Junk Synchron is a Machine-Type monster. Recently revealed Synchrons, "Change Synchron" and "Bri Synchron", have very little known about them.

Known "Synchron" Monsters are: "Junk Synchron", "Nitro Synchron", "Turbo Synchron", "Hyper Synchron", "Road Synchron", "Drill Synchron", "Quickdraw Synchron", "Fleur Synchron", "Change Synchron" and "Bri Synchron".