Quiver

The Quiver is a SkyBlock Menu Upgrade that appears in the bottom right of the main menu once you unlock it at. It allows you to put up to 45 stacks of Arrows, Toxic Arrow Poisons, Prismarine Shards, Slimeballs, and/or Magma Cream into it, which will be automatically used when firing a Bow. A stack of enchanted arrows will be shown instead of the Skyblock Menu when you hold a bow once this upgrade has been unlocked.

The Quiver can save a lot of inventory space if you have large quantities of projectiles.

Simillarly to sacks, if you have space left on your Quiver, arrows picked up will be deposited in there instead of in your inventory.

Obtaining
Like the Accessory Bag, the bag becomes larger as players progress in their Collection.

Trivia
The Quiver cannot store Ender Pearls for the Ender Bow, mainly because players figured out that they could use it as a second inventory when farming Endermen for the Aspect of the End.