Simplify the following text for a Grade 12 native English-speaking person.
Original: Vibraphone mallets usually consist of a rubber ball core wrapped in yarn or cord and attached to a narrow dowel , most commonly made of rattan or birch ( other materials , such as nylon , are sometimes used ) .
Simplified: They usually consist of a rubber ball core wrapped in yarn or cord and attached to a narrow dowel , most commonly made of rattan or birch ( other materials , such as nylon , are sometimes used ) .