Pearl’s Superior Shell Technology utilizes a proprietary technique for achieving the ultimate air chamber. It begins with select woods chosen for their unique acoustic attributes, milled to precise thickness with overlapping scarf joint seams, for a perfect air-tight fit. The wood plies are saturated with Pearl’s proprietary “AcoustiGlue” that permeates every pore and dries to the exact consistency of the wood for optimum resonance. Finally, the plies are formed in high-temperature molds with 1000 PSI of hydraulic pressure to produce perfect drum shells that exhibit superior tone, optimal resonance and extreme strength.