The X-02 is a 600 gram ranked firework, 100 grams above the 500 gram limit that customers can purchase without a necessary license. The firework's tagline is "So explosive, Uncle Sam wouldn't approve!".
The X-02 is completely banned in 17 of the 50 states in the US. While is is never mentioned which states are the ones that have banned it, it is clear that California is not one of them, as the series takes place in the fictitious Los Angeles suburb of Skyler City.
The firework appears in the episode "Fireworks", respectively. In the episode, Jonah shows off the firework to the gang during a pool-party at Lenny's house. He states that he bought 20 of them for only $5 from a "guy with a really long beard in a shack on the side of the road", clearly implying that the entire thing was a scam that Jonah has fallen for (this is actually the second "bargain" that Jonah fell for in the episode, the first was during the episode's prologue, when he spent $14 on a throw-away pool from Flawmart and completely destroyed it after only one use, causing the pool party to be moved from his house to Lenny's). While showing off the firework to everyone, Lenny returns from the neighbor's house next-door to see Jonah standing next to the charcoal grill with the firework. Due to Jonah's lack of self-awareness and clumsiness, especially when it comes to fire (ironically, as Jonah is a firefigher), Lenny immediately becomes panicked and runs towards Jonah to get him to move the firework away from the grill. However, as he does so, he ends up tripping over Jonah, causing Jonah to trip over and the firework to fly out of Jonah's hand and right into the grill, igniting it much to everyone's horror. Even though the firework ends up being a dud (not surprisingly, due to the clear implication that Jonah fell for a scam), a house is imploded next to where the firework lands while Synopsis Productions films a scene for the soap opera Silver's Anatomy, causing everyone to believe that the firework caused the house to explode, thus killing innocent people. However, the gang later figures out that the firework was a dud (much to Jonah's dismay) and that the house implosion was staged by a TV production company.