Which of the following thread sizes is NOT used in the telecommunications industry?

In the telecommunications industry, specific thread sizes are commonly used for various types of equipment and mounting processes. Metric thread sizes, such as M6 and M5, are standard for many applications, as they align with international requirements for component compatibility and ease of use in different regions.

Similarly, the 12-24 thread size, which refers to a unified threaded screw with 12 threads per inch and a major diameter of 0.216 inches, is also utilized in various telecommunications applications since it aligns with standard inch-based measurements commonly used in American manufacturing.

On the other hand, the 10-40 thread size is not typically found in telecommunications. This size signifies a unified number thread (10 threads per inch with a specific diameter of 0.190 inches) but does not align with common practice in the industry. The other specified thread sizes—M5, M6, and 12-24—are regularly implemented in telecommunications for secure and reliable connections, whereas the 10-40 thread size is less relevant to the specific requirements and standards in that field.