This FB221 Flybar for HDA for HD1801 Speakers attaches to the HDA loudspeaker and the HD1801 Subwoofer so that they can be suspended overhead with the ACC-R280S rigging kit. Two FB221s are included in the optional kit (BH# MAACCR280S). Purchasing additional FB221s will allow you to hang (fly) up to 4 HDA speakers.