Bests & Worsts Reviews from Amazon

I bought these for college. I thought they would be easier to use than the traditional erasable ink pen by paper mate. They are nice and convenient. The problem is if i left them too close to a heat source or rather the notebooks i used them on to take note. The ink disappears when exposed to heat. Like a heater vent in the floor or in the car where the sun can heat the note book up. I lost half my notes because of this. If you think about it that is how this product works. The friction from the rubber end against the paper warms up and the tadaaaa the ink is gone. I took a test once the professor left the test in her car and yeah I got a zero.