The ProsKit 902 201 Lunar Dies Set is a must-have for anyone in the industrial and scientific fields that require a reliable threading die set .Based on my observations they are durable and easy to use, making them ideal for heavy-duty work. The set comes with a variety of sizes and the die heads are interchangeable, making it a versatile addition to any workshop. The only downside is that they can be a little pricey, but the quality and durability make it worth the investment..