The band Krokodil was an influential group, the first to bring progressive rock to Switzerland. Composed of Zürich-scene veterans Hardy Hepp, Walty Anselmo and Düde Dürst with Mojo Weideli and English bassist Terry Stevens, Krokodil used exotic elements like the sitar. The Swiss psychedelia scene produced bands like The Shiver, Brainticket, Ertlif and Flame Dream. Bern's Sinus Studio was long the most influential studio in Switzerland. The Swiss sound of hard rock included bands like legends Toad, a bluesy band known for their debut single "Stay!". Mark Storace's Krokus, however, quickly become the most popular Swiss hard rock band, eventually incorporated heavy metal with 1980's Metal Rendez-Vous. Their 1983 Headhunter sold two million copies, making it the best-selling Swiss record in history and breaking the band into the United States and other countries.