The urumi is a double-headed hourglass drum from the state of Tamil Nadu, South India. Two skin heads are attached to a single hollow, often intricately carved wooden shell. The preferred wood is jackwood, although other woods like rosewood may be used. Both left and right heads are usually made from cow hide that is stretched around a thin metal ring. The outer circumference of each head is perforated with approximately seven to eight holes. The two heads are held in tension by a continuous rope that is woven around the drum in a V-shape pattern. Additional small coils of string or metal are tied around each pair of ropes near the left head. These coils can be slide horizontally along the length of the drum, increasing or decreasing the tension between the heads as necessary. For example, during the monsoon season the drum heads will slacken so much that the instrument becomes unplayable. Using these coils drummers can easily rectify such problems.