Anti Scale Systems with PROPORTIONAL DOSING. European made, 3 piece, transparent and blue housing, ports 3/4″ BSP brass inserts and pressure relief. For the treatment of drinking water, in compliance with EU directive 98/83/CE. The Atlas Filtri proportional dosing system is equipped with a special suction device which makes use of the “venturi effect” dosing the main water flow with polyphosphate in accordance with the European regulations thus reducing scale. Maximum hardness is 500ppm.