APEC FI-PHPLUS-QC US MADE 10" High Purity pH+ Calcium Carbonate Alkaline Filter with &frac14;&rdquo; Quick Connect For Reverse Osmosis Water Filter System (For Standard System, Replacement Filter Only) Increase ph level of the water by adding calcium carbonate mineral back into the water Made of 100% US-Made high purity calcium carbonate to effectively neutralized acidity Friction-welded construction with no glues or binder to provide reliable, no-leak seal Quick connection fittings for easy leak free installation A perfect add on filter to compliment any existing or new ro Drinking water systems - (filter only)