A Customs, like all Zildjian cast bronze cymbals, are individually poured and cast from raw molten metal. Each casting is cooled and sorted by weight for each cymbal model. Castings are then put through a complex sequence of heating, rolling, shaping, hammering, and lathing techniques unique to each cymbal range. Cast bronze cymbals have a rich, full-bodied sound that improves with age. They also have greater projection, clarity, and durability than any other cymbals. Zildjian cast cymbals are made from the Zildjian secret alloy, which comprises 80% copper, 20% tin, and traces of silver.