Wider Influence: Increases the range of the Monkey Beacon, allowing it to affect more towers.
Jungle Drums: Increases the attack speed of all towers within the beacon's radius.
Sonar Beacon: Allows towers in its radius to detect camo bloons.
Monkey Storm Beacon: The final upgrade (Unlocked at rank 18) is the monkey storm beacon, which summons monkey storms by paying the amount of cash required to use it. And you can only have one Monkey Storm Beacon.