When they get to their rated torque they just vibrate and do not tighten any more. Personally i don't like them.
Tony.
ps. That's not to say they don't work but as I have a torque wrench which will do many jobs I think these are an expense you don't need as they only do one job.
they are only £15 and stop you over tightening the wheel bolts when using a bigger than 120NM impact gun.
Far quicker, lives with my wheel bolt sockets,
and no need to faff with a torque wrench which when you get it out you find it is probably not set to what you want.
Or if you do buy a torque wrench to use and keep set just for your wheels only, then that is far more expensive I have many tools that only do one job....
Spark plug socket
oil filter wrench
valve spring compressor
7mm brake allen key
brake piston pusher
brake pipe tool
etc etc
personally I do like them....