Reverse Osmosis Revolution 3/4" Port Dual Stage Whole House Water Filtration System with Sediment & CTO Filters Powerful 2 Stage Whole House Water Purification system with 3/4" valves Comes with 1 Year filter supply (extra 3 sets) 1st Stage: Quick-Connect 5 micron sediment filter. Dust, dirt, silt, sand, rust and scale particles are trapped here in a filter which also extends the life of the system. 2nd Stage: Premium 5 Micron High Dirt Capacity CTO Block Filter Whole House filter system used standard 10"x2.5" cartridges