H2O (H2O-US4-13) Inline 5 Stage Under Sink Filter (Replaces NSA 100 Models)H2O Water Systems H2O US4 13 Inline 5 Stage Under Sink Filter Direct replacement for discontinued NSA 100S and NSA 100SX models with proven 20 year track record 2 GPM Flow Rate 3 Year Filter Life NSA 100 Retrofit Complete Install Kit The H2O US4 13 (model H2O US4 13) connects inline with your existing faucet using the same tubing dimensions and fittings as the original NSA 100S and NSA 100SX systems. This five stage under sink filter delivers