The shape of the edge is one of the most important factors that influence the sound of the drum. Since the heads provide the important source of vibration, the shape of the contact point of the head and the shell determines and defines the sound. This is why TAMA worked so long to achieve the most functional shape for the drum head and rim. The image shows a sectional view of the drum bearing edge. As shown in Part A, the top edge angle is set 2.5mm inward from the outer surface of the shell. The edge is round collar cut to follow the natural shape of the drum head (B). This design, which creates a better fit between the drum head and the bearing edge, maximizes the drum's resonance. This bearing edge shape is part of our TAMA tradition and is key to providing TAMA's unique drum sound. 4.