Die Casting Unit Die Holders are for Zinc and Aluminum Die Casting. Single and double unit holders are designed for smaller die casting machines. (50-150 ton). Replacement Inserts are standard replacement units available in various sizes. Heavy-duty replacement units are precision made and completely interchangeable when used with their matching Die Holders. Popular sizes are in-stock for immediate delivery. Die Casting Components are everything you need for your Die Casting Units.