Sea Pearls uncoated lead dive weights are die-casted from lead that has been reclaimed from car batteries. However, lead in its raw form does not meet the standard for Sea Pearl's dive weights, so they add other elements like antimony and tin to derive the alloy required for proper hardness and appearance. Using immense pressure, the molten lead alloy is injected into multi-cavity molds. This process provides the best quality, most consistent weights in the industry.