What is incorporated in turnbuckle barrels to ensure cable terminals are screwed in adequately?

Witness holes are incorporated in turnbuckle barrels to allow for visual inspection of the cable terminals’ engagement. These holes provide a means to confirm that the terminals are adequately screwed into the barrel, ensuring proper tension and safety in the application. By seeing through these holes, users can verify that the terminals are securely fastened without needing to disassemble the turnbuckle, enhancing convenience and reliability in maintenance or assembly processes.

In contrast, other options do not serve this specific function. Sealants are typically used to prevent leaks, adhesives bond components together, and locking pins are used to secure parts against unexpected movement or loosening. None of these options provide the visual confirmation that witness holes do, which is critical for safe and effective operation of turnbuckles.