The Flash Explosion (サマーソルトエクスプロージョン Samaasoruto Ekusupuroojon?, "Somersault Explosion") is Guile's first Ultra Combo in Super Street Fighter IV. It is a stronger version of his Double Flash Super Combo.
Executed by charging down-backward then inputting a "delta" motion and all 3 kick buttons, Guile crouches before proceeding to deliver a multi-hitting Flash Kick. He then follows up with another multi-hitting Flash Kick, this one done in a similar manner to Charlie's Somersault Shell. If this lands, Guile then finishes with a final, powerful Flash Kick ("Strike!" or "Final!", depending on the game's version) which hits only once but deals massive damage. The move itself is somewhat similar to Double Flash via its "Strike" version, with the main difference being the addition of the Charlie-style Flash Kick in between.
The animation mechanic makes it tricky, but not impossible, to combo into and deal the maximum damage possible; the Level 3 Focus Attack and Double Flash are both ideal combo starters. It also makes a suitable punisher and, with practice, can be an efficient anti-air. As with the Flash Kick, missing results in a wide window of vulnerability to counterattacks, so the move must be used carefully.