Perfect Fit: Compatible with all PUR, PUR PLUS faucet water filter systems (classic, advanced, vertical horizontal), including FM3700, PFM400H, PFM350V, PFM100B, FM4000B, PFM450S and more. All manufacturers' names and part numbers are used for compatibility information only Save Your Bills: 2 Packs work as well as the original filters, but at a lower cost. Filter up to 100 gallons of water or replace it every 3 months Powerful Filtration: NSF Certified activated carbon and ion exchange system reduces 99% of lead, chlorine, rust, sediment, etc (over 70 impurities), greatly improving the taste and odor Better Filter Process: Advanced structure pass through the water smoothly, which ensures stable and continuous clean water flow Easy to Replace: No tools needed. Unscrew the top cap to get out the old filter and insert the new one into the faucet mount until it clicks, then tighten the cap