Neural-inhibitor collar
From Halopedia, the Halo wiki
Neural-Inhibitor Collars are thick bands of metal that, when clamped on the neck, stop any neural signals that aren't necessary for continuation of life, utterly paralyzing the subject. The UNSC makes them standard issue for capture of dangerous felons.
General Graves used them when he tried to capture the Spartan unit Blue Team.[1]
