The khol is a drum with a hollow wooden body, with drumheads at both ends, one far smaller than the other. The wooden body consists of a single block of wood generally made from local trees viz. Saal, Kothal. (The drumheads are made of cow skin, and are three-layered and treated with a circle of rice paste, glue, and iron known as syahi. Some modern instruments are made with a fibreglass body and synthetic drumheads.