That line is fine if the bolt winding itself loose is your only failure scenario, but some might have others as well. What of they clamp a part that can subtly

That line is fine if the bolt winding itself loose is your only failure scenario, but some might have others as well. What of they clamp a part that can subtly deform in certain exceptional situations? Then you could have a bolt with zero tension that is still perfectly aligned with the marker line from when it was properly torqued. What I find somewhat surprising is that they make the "ok" indication black. The cry for attention state in red seems nicely intuitive at first glance, but given the market they serve they should be far more concerned with false negatives than with false positives and I imagine that it would be very easy for dirt or bad lighting to make a red indicator remain unnoticed in an inspection. Perhaps the color choice is an inherent property of the chemistry involved?