The Dragon Helmet is one of the four elements of the Hyribead hidden on the planet of Cronos. It renders the wearer invulnerable.
Machine Robo: Revenge of Cronos cartoon
The Dragon Helmet was accidentally discovered by Leina Stol, Kempō Robo and Fire Robo in a ruined temple near Emerald City. The Gyandlar captain Garudi found the group and attempted to take the helmet for himself; however, he was unable to injure Kempō Robo, who had donned it, and it even proves undamaged after a huge missile attack from the Varigale-X. The Four Treasures of the Mysterious Ruins It was then placed securely onboard the newly-completed Battle Base; when Ruby Man stood near it the helmet began glowing. The Secret of the Jewel People Amber Man later listed it as one of the four elements of the Hyribead. Save Amber Man, Blazer Cannon! Grujios attempted to steal it and the Phoenix Armor from the Battle Base using the possessed bodies of Harley Robo and then Leina; Rom Stol was able to knock the Dragon Helmet from his hands, though the Gyandlar escaped with the Armor. Close Call, Land Commander 5! However, a second raid by Grujios was more successful,Baikanfu - Cry of Anger! and he was able to get the Helmet to Gadess, giving the Gyandlar commander complete access to the Hyribead. Mighty Fortress, Heavenly Sword - Jet Don't Die! However, Rom was able to vanquish Gadess by combining his Wolf Sword with the Star Sword of his brother Guardi, taking back the four Hyribead elements - which he then used to restore Cronos. The Final Battle of Cronos