Safety device using a warning streamer for testing the soundness of industrial non-metal slings; predictable pre-failure warning indicator using a warning streamer for use with an industrial sling; proprietary warning system being incorporated into an industrial non-metal sling and being designed to fail before the load-bearing core of the sling fails in order to warn users that the sling may be unusable at its rated capacity by providing a visual indication via an elongated warning strand; safety indication device using a warning streamer that allows a user to conduct a non-destructive pass/fail inspection of an industrial sling especially for use with non-metal or synthetic slings; warning aid utilizing a warning streamer that can be manufactured into an industrial sling for providing physical and visual feedback to a user when said industrial sling has been damaged by, for example, an overload condition, abrasive wear, exposure to chemicals/acid, or an environmental condition such as excessive heat or cold, pollutants, or ultraviolet sunlight