Product has been around for a while perhaps not the video. Have you seen the price

Not the same [because these were developed to indicate actual failure rather than lack of tension] but it reminded me of the 'bleeding bolt': **LINK**

MichaelG.

[disclosure of the ludicrously long URL omitted, for clarity]

I investigated both with a job a few years ago, where we needed bolts to shear off at a known load. It proved to be rather difficult to make sure that they broke a reliable load (within 5%). In the end we had to get the bolts made, then reduced in diameter with a rounded slot, the diameter being read off a table dependant on the tensile strength of the batch. Makes for expensive bolts, but no commercial system we could find was reliable enough.

The bleeding bolts are good for fatigue, and the dot ones are tensile indicators, but a known fracture load is surprisingly difficult. Most materials have a known minimum strength, but rarely is the maximum tightly controlled.

Regards

Richard.