The openings on this filter are 1/4" FPT standard threads and will fit any 1/4" male pipe thread fittings. It utilizes NSF listed 20x50 mesh coconut shell granular activated carbon which is acid washed to remove any impurities prior to use in this product. This filter has been tested to ANSI/NSF Standard 42 for 3,000 gallons of performance for taste and odor. This testing assures you the customer that you are receiving the highest quality product available and in testing it has passed various structural tests which insure that this filter meets the rigorous requirements set within the standard to help insure that this filter will remain leak free though-out its useful life. Compare this filter to similar products sold under brand at your local big-box retailer for many times the price. These filters are great for use behind your refrigerator, for use with small automatic coffee making equipment, and as the final filter in most undercounter reverse osmosis systems.