Pentek - CRF20-BB - 20" x 4.5" Radial Flow Carbon BlockPentek High Capacity Radial Flow Technology CRF20 BB 20" x 4. 5" Radial Flow Carbon Block Filter Engineered for high flow commercial and whole house applications where chlorine, chloramine, and sediment reduction can't compromise flow rate 200,000 gallon capacity 25 micron filtration Radial flow design for low pressure drop Advanced granular activated carbon The Pentek CRF20 BB uses a radial flow configuration that allows water to flow from the