Gabi Tu

Gabi the Robot or better known as Gabi Tu is a character who appears in every 5th book after The Roller Coaster Jet, Silver Bullet, Boomerang and Kingda Ka.

Books that Gabi are in

 * The Roller Coaster Jet, Silver Bullet, Boomerang, and Kingda Ka
 * A Peaceful Vacation
 * Africa!
 * The Diamond Hunt
 * Future Into the Twin Cities
 * Alien Attack!