Chinese stealth armor was used during the Chinese invasion of Alaska and was the Chinese solution to invasion by U.S. forces in power armor. It was available to elite Chinese Crimson Dragoon troops as well as the Black Ghost counter-insurgency/terror units before and during the Great War.
The following is based on Van Buren and has not been confirmed by canon sources.
Earlier Hei Gui models were also used during raids against the Hoover Dam secret laboratory and Limit-115 laboratory.
The armor is a form-fitting armored jumpsuit, with stealth camouflage system embedded. It generates a modulating field that transmits the reflected light from one side of an object to the other, making a person much harder to notice (but not completely invisible). The technology was the basis for the unstable "Stealth Boy" wrist units developed in the U.S.
pcps3xbox360 If the armor breaks while the player has the stealth field activated, there is a possibility that the stealth field will stay active even after changing to a different piece of clothing or exiting sneak mode. This can be fixed by repairing the armor and toggling sneak mode while wearing it, or loading an earlier save. [verified]
pcps3xbox360 When a companion has the armor equipped and is crouching (activating the stealth field) you can trade items with them and swap the armor with another clothing article and when exiting dialogue the stealth field will remain whenever the companion is crouched. This is useful if you want to sneak through areas with a high concentration of enemies (such as Evergreen Mills) without the possibility of the death of the companion. [verified]
pcps3xbox360 If you pickpocket a stealth suit from a Crimson Dragoon, the stealth field will not activate when crouching, and the suit's stats are identical to those of the recon armor. Additionally, it lists under effects on the Pip-Boy as "Initiate's Armor". [verified]
pc While performing the perk "Mister Sandman" with the stealth suit the lower part of the suit will be detached from the player character's skeleton. [verified]
pcps3xbox360 When picking up the armor, it will spin when being held, making full circles, until it is dropped. This may be due to selecting the rounded face plate of the armor when it is on the ground, selecting the back or bottom of the armor allows it to be moved normally. [verified]
xbox360 If you stare at the ground and swing a knife while crouching in first person view, a part of the suit will clip into view. [verified]
ps3xbox360 Sometimes when equipping enclosed headgear like a power helmet, switching to the stealth armor, and removing the headgear will seem to have made the player character's head vanish. [verified]
To fix this bug, remove the helmet and the Chinese stealth armor, and then re-equip it again and the helmet should be back.