It is the name we use for all our coils that go above and beyond with there coil circuiting configurations. This coil is for an old commercial Rheem HVAC unit in a location where they are unable to change the RTU, replacing the coil was the best and only option. At Nationwide coils we have experience duplicating the most difficult HVAC coils for seamless replacement and installation of the new coil. Any questions? Do not hesitate to ask us! We look forward to helping you with all of your HVAC coil needs.