Clockport Adapter for Amiga 500/1000
The Clockport Adapter for the 68k socket of your Amiga 500 (or Amiga 1000) allows the use of clockport modules for the Amiga 1200, e.g. Silversurfer, Delfina or Subway. The interface features two clockports, so you can use two clockport modules (provided the driver software supports this).
Source: http://www.vesalia.de/e_a500clockport.htm