Purenex 1C-1GAC-1S 5-Stage Reverse Osmosis Filter Replacement Set for Carbon and Sediment 1. Sediment Filter 5 micron 2.5-Inch x 9.75-Inch 1. Carbon Block Filter 2.5-Inch x 9.75-Inch 1. GAC Coconut Shell Filter 2.5-Inch x 9.75