The first appearance of an armored superhuman restraint unit was in the pages of Marvel UK's The Mighty World Of Marvel, during the events of the Jaspers' Warp story arc. In this tale, insane reality warper, Jim Jaspers became the Prime Minister of the United Kingdom and turned the UK into a fascist state. As PM, he enforced "Super Hero Legislation"; using armored agents of S.T.R.I.K.E., the UK division of S.H.I.E.L.D., to hunt down and detain superhumans within the UK. These anti-superhuman agents were called "Beetle" squadrons, due to there beetle head shaped helmets, and were best known for gunning down Tom Lennox, Betsy Braddock's lover.
During the events of Marvel Comics' Civil War crossover, the United States government passed a Superhuman Registration Act and used a division of S.H.I.E.L.D. agents, recently trained to deal specifically with superhuman threats, to enforce the law. These foot soldiers of S.H.I.E.L.D., known as (Anti-)Superhuman Restraint Unit, and more commonly Cape-Killers, were spread out across Marvel comics, and came into conflict with various superpowered individuals throughout the event and into the subsequent Initiative story arc.
Not much has been revealed in the comics about the Stark Enterprise's armor which is used by the Cape-Killers. During appearances of this unit, two different styles of helmet have been used; a Riotsquad style helmet and, more commonly, a helmet with a Filter style gas mask.
These suits are out-fitted with internal comm systems, and hover discs that give the wearers the ability of flight which have been seen in various comics.
The armor suits have been shown to be susceptible to power surges in several issues, and Nick Fury, S.H.I.E.L.D.'s former director who went into hiding after the events of the Secret War limited series, would later develop a device that transmitted an electromagnetic overload pulse-broadcast straight into their comm systems, shutting down their suits and frying there electrical systems that was show to take down several unit members at once.
It was later shown that former Stark Enterprise employee and a designer of the Cape-Killer armor, Kenny has an override code on his high tech palm pilot that can freeze the suits.