Eheim filter pad set professional 3r this pad set consists of 1 blue and 4 white polishing filter pads that can be used in the professional 3 250 350 600 and professional 3e 350r changing your filter media regularly can extend time between cleaning and make sure that your fish are enjoying the most sanitary environmentr blue pre filteration through foam filter padr on account of the large upper pre filter the particles of dirt are extracted from the in flowing water before the actual filtera