Camo Bloons popped by this tower permanently lose their camo status, and can be attacked by towers without camo detection.
~ Official Description
Signal Flare is the third upgrade on the second path for the Mortar Tower in Bloons TD 5. It costs $425 on Easy, $500 on Medium, $540 on Hard, and $600 on Impoppable. In Bloons Monkey City, it costs $750 normally and about $640 when favored. It allows the Mortar Tower to detect and attack Camo Bloons. In Bloons TD 5, the Mortar Tower cannot target camo bloons without this upgrade. When a bloon is struck by with this upgraded tower, the bloon loses its camo status and turns back into a normal or Regen Bloon (depending on its initial status). Towers without camo detection can attack the once-camo or once camo-regen bloons (regen removal only for Bloons Monkey City's Monkey Knowledge Packs).