*The top of the separator features a
  nylon wheel for easy rolling across
  the top pulley line, while the bottom
  is designed to move with the lower line
  to support the weight of wet clothes,
  keeping both lines linked together to
  prevent sag and drag
*One separator is recommended
  approximately every 10-15 feet for
  optimum performance of a pulley
  clothesline system.
*This product is easy to use and is
  uniquely designed to resist accidental
  fall-off.