Heartwood Armor (5e Equipment)
From D&D Wiki
Armor (medium or heavy, but not hide), common (requires attunement by a Druid)
This armor is comprised of very durable wood. Due to its material, it is ideal for druids. Armor made from heartwood weighs half of it's normal weight, and any medium armor that imposes disadvantage on stealth checks no longer does when made of heartwood.
Due to being made of wood however, attack rolls that deal fire damage are made with advantage against you while wearing this armor.