010135001599 PRIMOS 159 The Sound Plate automatically positions the call in your mouth at the right place and angle making calling elk easier. The Ivory Plate Single has a Sound Plate set at 30 degrees which is perfect for cow calf talk and satellite bull bugles. Features: 30 Degree sound plate angle and single-reed design allows you to reproduce cow calf and satellite bull sounds all with one callUPC: 10135001599PRIMOS 159 010135001599.