If held by a Flying-type Pokémon, it takes 1× damage from Ground-type moves if its secondary type is not weak to or resists Ground-type attacks.
Even if the holder has Klutz or is affected by Embargo, its Speed is still halved by the Iron Ball.
Generation V onward
If held by a Flying-type Pokémon, it takes 1× damage from Ground-type moves, regardless of its other types. This does not apply during Inverse Battles or if the holder is grounded by any other effect.
An item to be held by a Pokémon. It lowers the holder's Speed stat and makes the holder vulnerable to Ground-type moves even if it is a Flying type or is levitating.
Halves the holder's Speed stat. If the holder is off the ground, it will be grounded, meaning it can be affected by Ground-type moves, as well as the Spikes, Toxic Spikes, and Sticky Web statuses.