Aquasana Replacement Filters Stage 1 and 3  for Aquasana OptimH20 Reverse Osmosis Water Filter Genuine replacement Filters Stages 1 and 3 for Aquasana OptimH20 Reverse Osmosis Water Filter: AQ-RO-3 Use only genuine Aquasana replacements - untested replacements are not certified for performance capacity or contaminant removal Replacements made easy - no tools or plumber required - replace membrane every 6 months Removes over 95% of fluoride PLUS up to 99% of 87 other contaminants like lead, mercury, asbestos, and more Full system NSF certified to standards 42, 53, 58, 401 + P473 - will not leach contaminants back into your water