COMPATIBILITY: The PDC51V1 demineralization is compatible with Protec Demineralization Humidifiers V4600/V5100/VUL575 Series! REDUCE THE WHITE-DUST: PDC51V1 Demineralization Cartridges may help capture the minerals before they are released into the air and settle on surfaces. Water demineralization helps remove white dust. OPERATING EFFICIENTLY: Demineralization For results, replace as necessary (every 2-4 weeks, or 15-30 fillings under normal use) or when the humidifier has not been run for an extended period of time. HOW TO INSTALL: Remove the tank and empty all water from the reservoir, Insert the into the humidifier reservoir, Replace the water tank and wait 15 minutes for the water to pass through the filter before restarting the humidifier. Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:blue Material:ABS Package Contents: 3 x Humidifiers Filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.