What's thread protector?

For products with threads produced and processed in batches, products must be stored, packaged and transported before reaching users. Collision and sand erosion will occur during this process. The processed external thread (generally pipe type) is easy to be damaged. Especially the internal thread is polluted by sand [such as hydraulic pump]. Therefore, people use plastic to make a sealed pipe head to cover the external thread, and make a plastic part to screw in the internal thread to protect the thread from damage, and also protect the internal from sand erosion.