Donguri Arms (ドングリアームズ Donguri Āmuzu, lit. "Acorn Arms") is an alternate acorn-based armored Medieval Squire form of Armored Riders. Accessed through the Donguri Lockseed, this form's Arms Weapon is the Donkachi, while the helmet the Rider wears is the Dome Casque (ドームカスク Dōmu Kasuku) with the Nut Eye (ナットアイ Natto Ai) visor. While it is the default form of Armored Rider Gridon, it can also be used by other Riders.