Shackle

The Shackle is an Accessory that grants 1 point of Defense. It is dropped by Zombies somewhat rarely, although it's easy to acquire in plentiful amounts if you venture into the wilderness during a Blood Moon and keep killing zombies.

They become obsolete near the end-game, as the player can obtain an Obsidian Skull or Cobalt Shield, which grant immunity against burning blocks or knockback, respectively. They cannot be destroyed by throwing them into lava.

They can be sold to a Merchant for 3 Silver Coins.