The tips on these markers are "crush resistant". Students don't waste ink from writing with smashed tips that no longer write well, as happens with other markers.
One of our student markers can write as long as two "teacher sized" dry erase markers. Our markers can last anywhere from a couple months to a year in normal classroom use.
There can be major differences in the quality of a marker. We have heard reports of other dry erase markers only lasting for a few days. There are also differences in how distributors handle the markers. All dry erase markers have a limited shelf life. Our markers have up to a 3 year shelf life. If the retailer you buy your markers from is selling you stale stock that was manufactured a couple of years ago, your markers can be used up before you even begin using them.