Amulet of Growth and Reduction

Whilst wearing this amulet, made up of brass discs of varying sizes, you may use your action to freely shrink or enlarge yourself. You may grow up to one size larger, or shrink to one size smaller, than your ordinary height, as if by the Enlarge/Reduce Spell. There is no limit to the length of time you may spend in these sizes, or how many times you can change size, however, you will revert to your normal size if you fall unconscious or die.