Vault Jumpsuit

The Vault Jumpsuit is a set of standard clothing worn by all inhabitants of Vault-Tec Vaults. The number of the Vault is on the back of the suit. Vault suits from Fallout and Fallout 2 were depicted as skin tight, but they were not so in Fallout 3. Thus is likely just a difference of design interpretation, though some speculate that the Vault suits in the Capital Wasteland were just made differently in-universe.

Fallout 3
Each suit can be used to repair other jumpsuits.

Vault 87 Jumpsuit
These suits were worn by the ill-fated subjects of Vault 87's Evolutionary Experimentation Program.

Although the Vault 87 Jumpsuit was put into the game's files, the game itself offers no opportunity for the player to obtain one, and the only one seen throughout the game is worn by Fawkes, ripped to shreds by his enormous super mutant body. While Fawkes' suit is grey, the wearable version is blue. It is likely that the color of Fawkes' suit simply faded with the passage of time.

Vault 92 Jumpsuit
The Vault 92 Jumpsuit is unobtainable because the Vault 92 inhabitants are dead and their clothing is decayed.

Vault 101 Jumpsuit
The Vault 101 Jumpsuit is the standard clothing given to the inhabitants of the Vault 101.

Vault 106 Jumpsuit
The Vault 106 Jumpsuit can be found on the corpses of the insane survivors in Vault 106.

Vault 108 Jumpsuit
The Vault 108 Jumpsuit can be found on any of the various Garys within Vault 108. Unlike other Jumpsuits, 108 is extremely dirty, presumably because of the state of Vault 108.

Vault 112 Jumpsuit
The Vault 112 Jumpsuit is distributed by the Robobrain upon entering Vault 112.

It is possible to get an unlimited number of the Vault 112 Jumpsuits. Simply drop the one the Robobrain gives you and talk to it again. You can do this over and over again, but it isn't actually that useful as the uniforms aren't worth much.

Appearances
Vault Jumpsuits appear in all Fallout games. However, in Fallout and Fallout 2 they are worn by the player character by default and only in Fallout 3 appear as actual in-game items.