minecraft-packets/minecraft-packets/data/pc/1.12.2/from-server/entity_equipment/5.json

An easy way to query PrismarineJS/minecraft-packets

{
  "entityId": 2321,
  "slot": 0,
  "item": {
    "blockId": 261,
    "itemCount": 1,
    "itemDamage": 0
  }
}