Amazon with Flymoo Store has the FLYMOOO Bath Faucet Water Filter with 8 Stages & 2,500 Gallons of Filtration (GLQ-White) for $40 - 50% off with coupon code 6ZPVS5C5 at final checkout = $20 with free shipping on $35+ or with Prime. Fits the majority of common bathtub faucets.