Simple and dependable You re going to love the way this call works. The Sonic Dome Series has been designed so the call is automatically positioned correctly in your mouth. The dome gives you a consistent distance between the reeds and the roof of the dome for an incredibly consistent sound. The Sonic Dome Series calls use latex reeds. These calls will do it all. Features: - Two Latex Reeds - Reproduces Estrus cow and herd bulls sounds.