this be a extremely well-designed and well-built sander . change the belt could not be easier . the speed control be simple to adjust , and be variable by the amount of tension place on the trigger .  this sander feel great out of the box , sand flat and be smooth-running . I do heavy duty sanding , and this be the tool for the job . if I could I would give more than five star for Bosch tool . I highly recommend it .