I was afraid to splurge by controlling this electric gum but I am amazed by its effectiveness. The fine tip erases small details. However, we must think of maintaining the sheet at the risk of offending his drawing. The gum does not wear out too quickly, especially if you do not use too large to erase surfaces. Simple to change the eraser (simply pull on the tip that holds the eraser). The device comes with 8 spare tires but no batteries. It will put 2 AAALR03 battery types (those of TV remote control).