I've been using this sander since 1976.  Back then, it was made by Rockwell.  Porter Cable bought out their tool division several years ago.  They know a timeless design when they see one and this sander needed no improvement.  This is a heavy, heavy duty orbital sander.  It uses its own weight to do the job.  Using half sheets of sand paper, it cheaper to operate over the long run over having to buy round sheets that come 4 or 6 to a pack and can be pricey.