“If nothing else, you can take a beating! Assuming you'll be dealing with more than simple foul language hurled in your direction, gaining a permanent bolster to your Damage Resistance is just like having a thick skin of armor. A fantastic way to spend a Perk Point or five.”— Fallout 4 Vault Dweller's Survival Guide description
In each respective game, the chest emblem has a number signifying a vault. Fallout and Fallout 2 each have a 13 on them, representing Vault 13. In Fallout 3, the chest emblem has a 101, representing Vault 101. In Fallout New Vegas it is a 21, representing Vault 21. And in Fallout 4, the Vault Boy's chest emblem has a 111 on it, signifying Vault 111.