I did an experiment on mine a while back. Compared to strap. Worked out about +/-6%. I know that's not great, but perfectly ok for my level of athleticism.
It depends a lot on arm hair and amount of sweat as to how well they work
I'm about as hairy as a newborn and sweat like the Duke of York.
@Sumo started
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I did an experiment on mine a while back. Compared to strap. Worked out about +/-6%. I know that's not great, but perfectly ok for my level of athleticism.