The Multi F and Multi FDX series offer such a wide selection of permutations, that they are amongst the most flexible multi-split systems on the market. Both systems allow maximum pipe runs of up to 25 meters for every indoor unit. The major point of difference between Multi F and Multi FDX is the latter's use of distributor boxes to increase the number of indoor units that a single outdoor unit can run - enhancing efficiency and minimising energy costs. They also utilise R410A refrigerant to enhance the systems efficiency and their compliance with the environmental legislation.