I purchased these leg warmers to wear on a local Run to the Pub race on St Patrick's Day.  They are made of a thin knit material that should hold up for a while.  My calves are 13.5 inches around and I would suggest not buying these if your calves are much larger as they are bordering on being too tight around my calves.  But I guess a little too tight is better then too baggy, and they are so long and tight I can pull them up and wear them as thigh highs.  BONUS.