Pendulum Zone

Pendulum Zone (ペンデュラムゾーン Pendyuramu Zōn) is a zone made for setting Pendulum Monsters. There are only 2 Pendulum Zones. When Pendulum Monsters are in both Pendulum Zones, they are treated as Spell Cards, thus they cannot be destroyed by battle (they are not treated as monsters), and can only use their Pendulum Effects, not Monster Effects. Pendulum Zones are usually on the end of the left side and the end of the right side on the Duel Disk.

Real Life
There are only 2 Pendulum Zones. When Pendulum Monsters are in both Pendulum Zones, they are treated as Spell Cards, thus they cannot be destroyed by battle (they are not treated as monsters), and can only use their Pendulum Effects, not Monster Effects. The blue diamond Pendulum Zone determines a Pendulum Monster in that Zone will conduct Pendulum Zone by it's blue Pendulum Scale and the red diamond Pendulum Zone determines a Pendulum Monster in that Zone will conduct Pendulum Zone by it's red Pendulum Zone.