The Beak is large metallic exoskeleton with black and yellow coloring. It has a helmet that resembles a bird.
The Beak suit is divided into two sections designed to be piloted each by Phineas and Ferb. The upper half controls the arms and torso, while the lower half controls the legs. When worn, the suit provides its users enhanced physical abilities, including:
After finishing the "Phineas and Ferb's edge-of-insanity, kiss-your-butt-goodbye, gravity's-a-stone-cold-sucker nightmare rail skate track obstacle course of doom", Phineas realizes that he and Ferb could get hurt if they use the track, so they reluctantly take the stairs back to the ground to revise their plans. They build a suit they can pilot to handle the obstacle course, by enhancing the user's reflexes and physical attributes. Isabella spots the boys using the suit albeit unaware of the "superhero"'s true identity, and dubs him "The Beak".
The Beak arrives downtown to tell Isabella about the Beak's true identity. Just as he tries to attract Isabella's attention, he's attacked by Khaka Peü Peü. A fight ensues in which the Beak is victorious. Phineas beats a swift retreat, stating to Ferb that they can't reveal the Beak's true identity at this crucial stage of the game without putting Isabella in danger.
After foiling some of Khaka Peü Peü's plans, The Beak is then confronted by "The Dangeraffe" (Candace), Khaka Peü Peü's new ally. Thinking Khaka Peü Peü captured Candace, they surrender until Candace leaves Khaka Peü Peü (after he called her a henchman). Another fight follows, during which Isabella is knocked off a ledge and the citizens are put in danger when Khaka Peü Peü fires a laser to knock down a billboard, giving The Beak two problems at once. Phineas exits the suit to save Isabella, while Ferb saves the citizens and the fight continues when Phineas returns. During the battle, Phineas realizes Khaka Peü Peü's motives and reveals their identity to end the conflict. Despite still wanting to battle, Khaka Peü Peü is forced to leave due to his wife. Agent P then takes control of the suit after Doofenshmirtz takes control of Khaka Peü Peü's hover craft.
In "Phineas and Ferb: Mission Marvel," the Beak (deployed using an upgraded version of the original, Beak Suit Mark 2) is donned by the boys to help the Avengers and Spider-Man when the superheroes lost their powers. The suit is also used in the battle against Red Skull, Whiplash, Venom and MODOK, but it is unable to handle blows made by Venom; it gets its arm ripped off and later part of its abdomen destroyed by Venom.
In "The Beak", CGI was used for certain shots of the suit. However, in Phineas and Ferb The Movie: Across the 2nd Dimension, CGI is absent and the suit is drawn somewhat slimmer.
The Beak combines elements of various superheroes: Iron Man's suit, Superman's relationship with Lois Lane, Batman's Batcave, and Spider-Man's theme song.
The first time the boys suit up in the Beak armor is a reference to a similar scene in the 2008 Iron Man film, complete with a similar guitar riff in the background music.
When Phineas used the suit, it altered his voice slightly. When Baljeet used the suit, his voice had no change at all. However, since the helmet was made for Phineas, it's possible that they had to modify it a little to fit Baljeet (as evidenced by Baljeet's entire face showing as opposed to the lower half, like on Phineas), thus removing any voice-altering properties.