Please note that this is the Narutopedia's article on the technique used by the Uzumaki. If you are looking for the article on the technique used through the Outer Path then you should head to Demonic Statue Chains.
Kushina using the chains in the real-world.
Kushina manifesting the chains in Naruto's subconscious.
Known by members of the Uzumaki clan, this technique moulds the user's chakra into chains which, after materialising, can be used for various purposes such as physically restraining targets, fight them directly or be used as a means of transportation. When used offensively, the chains are strong enough to damage Wood Release techniques as strong as the Sage Art: Wood Release: True Several Thousand Hands.
When using this in conjunction with her special chakra, Kushina was able to restrain Kurama in Naruto Uzumaki's mind. These chains also made up her seal, completely pinning the fox down with several spikes in her mind. Even while near death, Kushina was able to use these chains in the physical realm to restrain Kurama, enabling Minato to use the Dead Demon Consuming Seal. This involved five chains emerging from her back and burrowing into the ground, after which they would surface and criss-cross multiple times over the target, holding them down.