Im a big guy and chaff easily.  I bought these and the 5MAYI brand to see if something helped.  First time I wore these was before working an all day event on asphalt on the hottest day of the year so far.  I made the whole day without chaff much to my amazement.  I was chaffed within an hour and a half with the others the first time I wore those, and that was under regular work on a cooler day.