THIS UNIT ALLOWS NON DECA RECEIVERS TO BE CONNECTED TO SWM MULTI VIEWING ROOM SYSTEM. THIS SYSTEM REQUIRES YOU TO HAVE A SWM (single wire multiswitch) SYSTEM YOU WILL NEED ONE DECA UNIT FOR EACH RECEIVER LISTED HERE: EXAMPLE OF RECEIVERS THAT NEED A BAND STOP FILTER: H20 HR20 D12 R16.