Chain Helmet is a type of armor that provides players with protection against damage. Crafted using fire (which is not normally obtainable in survival mode) or more commonly found as loot in chests, this headgear offers slightly more defense than a leather cap but less than an iron helmet. It is part of the chainmail set, which is known for its distinctive, mesh-like appearance and can be repaired with iron ingots on an anvil or by combining two damaged helmets.
The numerical item ID for Chain Helmet is 302
Numerical item IDs will only work in Minecraft versions below 1.13.
The item ID for Chain Helmet is minecraft:chainmail_helmet
This is the spawn command to give yourself Chain Helmet in Minecraft which includes the Minecraft /give command. If you are using the Essentials plugin you will need to use /minecraft:give instead of /give