A Seithr Regulator (魔力調節器 Maryoku Chōsetsu-ki) is a device which moderates the amount of seithr that its wielder uses. These regulators prevents the seithr from their user's bodies from going out of control.
- Ragna the Bloodedge - visible on the backs of both his hands
- Nu-13 - visible as her eyepatch on her right eye. Has two more on her back when using the Lux Sanctus: Murakumo
- Mu-12 - visible on her pauldrons
- Izayoi - visible on her lower back
- The Origin - visible on her chest
- Kuon Glamred Stroheim - visible on the back of her head in her Code: Embryo outfit
- Kuon Glamred Stroheim Model Sheet 05