What does the double square symbol on tools indicate?

The double square symbol on tools specifically indicates that the tool's switch and gripping surface are designed to be non-conductive. This is a critical safety feature that protects users from electrical shock hazards, ensuring that the parts of the tool that a user interacts with do not conduct electricity. This is particularly important for power tools used in environments where users might be in contact with other conductive materials or where moisture is present, increasing the risk of electrical shock.

By having this non-conductive design, the tool meets safety standards that aim to reduce the risk of electrical accidents, thus enhancing the overall safety for the user and the work environment.