ABOUT THIS SYSTEM: Mix & Match Wall Mount and/or Ceiling Cassette for your custom system. Please select from below each of the indoor units. It is not required to use all four zones. The sum of the total indoor BTUs can not exceed 42K. Example: 6+9+24=39K BTU (suitable), 6+9+12+15=42K BTU (suitable), 9+9+12+18=48K BTU (NOT suitable). ____________________________________________________________________________________________________ ATTENTION HOME OWNERS: Purchase of this system will require a licensed technician. DO NOT underestimate the complexity when using a branch box. Protect your investment and only allow a skilled professional to do the installation.