The mbira is played with the two thumbs stroking down and the right forefinger stroking up. A mutsigo (stick) is used to wedge the mbira securely inside the deze. The mbira is usually placed inside a large calabash resonator (deze) to amplify it. Although the metal keys were originally smelted directly from rock containing iron ore, now they may be made from sofa springs, bicycle spokes, car seat springs, and other recycled steel materials. The mbira of the Zezuru group of the Shona people of Zimbabwe consists of 22 to 28 metal keys mounted on a gwariva (hardwood soundboard) made from the mubvamaropa tree (Pterocarpus angolensis).