Jarngreipr are two huge silver colored gauntlets that cover Minato's arms up to her elbows.
Jarngreipr enables the user to change its weight. However, this only applies to the Orga Lux itself and doesn't affect the user or others. Its cost is sleep, requiring the user to sleep based on how long it was used, and in some cases the sleep can be longer than 24 hours. Also, the user is unable to be wake up until the required time limit has passed.
Increasing Jarngreipr's weight allows Minato to deliver devastating blows, and coupled with her Genkuryuu, which is centered around twisting the body and utilizing circular movements, she can effectively keep on fighting without being troubled by its weight. She can also keep its weight at a certain point and then decrease it all at once to trick the opponent and block their attack.