This outfit is similar in appearance to the standard rags worn by the Children of Atom. Unlike regular rags, it grants 5 Radiation Resistance. It can be upgraded with ballistic weave but cannot be worn with any armor pieces other than helmets.
The Robes also have an unmarked special effect, which grants the wearer increased Radiation Resistance the more irradiated they are. This effect maxes out at 2500 rad resistance at the expense of having extremely low health, making the wearer practically immune to environmental radiation.
This effect has a second stage that only activates once the wearer becomes more irradiated than the first threshold, which can be accomplished by consuming irradiating items such as irradiated blood or durable sludgepak, or by firing the salvaged Assaultron head . Once the player character has surpassed 900 rads, the effects shown in the Pip-Boy do not change, but the player character becomes completely immune to radiation and their HP can be restored to its maximum amount.
In order to retain the immunity effect, the Robes must be worn at all times, and the player character's radiation level cannot be lowered back below 900 rads by, for example, RadAway, or taking rank 2 of Solar Powered which cleanses rads from 6 a.m. to 6 p.m. Once the effect is removed, the player character's HP immediately drops according to standard radiation effects.
While the effect gets removed by wearing power armor, it can be re-activated (by unequipping and re-equipping the robes) after exiting the power armor, as long as the player character's radiation level is still past the 900 rads trigger threshold.