Based on our own experience, we highly recommend these fire nozzle rubber gaskets for INDUSTRIAL and scientific use .They fit perfectly with our existing equipment, and are made of high quality materials that ensure long-lasting durability. The 5-pack offers a great value which is perfect for our needs. The only con we can think of is that it might not fit all nozzle types, so be sure to check before purchasing. Overall, these gaskets are a great investment that are worth every penny..