I have purchased over the past 5 years 20 of these items. The first group was a set of 15 from a vendor and I have purchased additional units for myself and other people. Of the 20 items all but 1 are full functional and in great working condition. They are very durable. They are used nearly every day in either a teaching learning environment by multiple people or by individuals who use them daily for multiple tasks. This is one great model from HP