This mod simply adds a keybinding to free up both hands. The items in your hands will be stored in some extra "slots" when first pressed. Press the key again to retrieve the items, swapping them with anything you might have picked up in the meantime.
Stored items are displayed to the right of the hotbar by default. They are not visible from you inventory screen.
Because some blocks can only be interacted with if both your hands are empty, especially if you need to sneak and click.
