Check the listing for details. Yamaha Stage Custom Birch 3-Piece Bop Shell Pack Raven Black. Condition: New. Listed at 599.99 USD. As with the introduction of Stage Custom in 1995, Yamaha once again sets the standards of value and sound. This Stage Custom inherits 100% birch wood, with upgraded metal parts. The shell is a key factor in a drum's ability to "rumble," or resonate. Accordingly, the Stage Custom employs 100% birch—a classic in the realm of high-class drum kits. Moreover, with its six-ply structure, the Stage Custom accurately conveys the vibrations produced at the impact surface, achieving performance that overwhelms anything in its class. The secret of Yamaha's YESS system is twofold: First, it provides minimum contact of hardware with shell; second, it connects that hardware at the nodal point* of the drum—the point at which it will not interfere with shell vibration.