Free Shipping Drop-Shipped Add to Cart Compare OptiPure CTOS-Q Replacement Cartridge for QTI-1 OptiPure MSRP: $197.48 Now: $110.73 Contact us for expedited shipping options. The OptiPure CTOS-Q is a quick-twist replacement cartridge for the OptiPure QTI-1 water filtration system. This filter reduces sediment down to 1/2 micron... MSRP: $197.48 Now: $110.73 Add to Cart Compare Qty in Cart: 0 Quantity: Decrease Quantity: Increase Quantity: Price: MSRP: $197.48 Now: $110.73 Subtotal: Add to Cart