Must have the ability to perform simple mathematical operations using units of American money, weight measurement, volume and distance. (ziprecruiter.com)
I have been using this unit for about a month and it's still going fine, so I don't know how often exactly they will need to be replaced. (thefashionablehousewife.com)
If you haven't used these units before, then we would recommend you try to get a curling iron that comes with a heat proof glove. (bestcurlingwands.org)