Made of heavy-duty industrial-grade tungsten steel for high strength and durability These tools are primarily useful for creating threads on steel, stainless steel, or other soft materials The 40-piece Metric Tap and Die Set comes in a molded storage case Ideal for re-threading fasteners and fixing holes, for auto and mechanical repair. Perfect set for both the professional and amateur tradesman. Known for their ease of use, these Tap and Die sets are the most commonly used style and are ideal for most hand threading applications.