It are designed to securely fit crucibles with a 50mm diameter, providing essential protection during high-temperature applications in laboratories. Made from durable porcelain, these lids offer excellent heat resistance and chemical durability, making them ideal for use in heating, calcining, and melting experiments. The 54mm diameter ensures a secure and snug fit, preventing spills and ensuring consistent sample integrity. This pack of 5 lids offers an economical solution for laboratories needing high-quality crucible accessories.