The S-Series from Kopf Percussion truly is in a class all it's own. It is noticeably different from it's tonal qualities to it's durable construction. To start with, the shell of these cajons are made from solid poplar rather than a plywood. The shell is also thicker than most other cajon shells. It is ¾” thick. The dual playing surfaces are constructed of Baltic Birch. Something else that sets these apart is the upholstered seat on top for the ultimate in comfort. Through and through, we set out to make this series “over the top” in quality of sound and craftsmanship.