APEX RF-1010 Carbon Block Filter Cartridge, 9-3/4" x 2-7/8", 5 Micron NSF approved, acid washed, high performance coconut shell activated carbon. Reduces fine sediment and chlorine taste and odor in residential and commercial drinking water High chemical absorption capacity. Fits all APEX countertop and reverse osmosis systems and most other standard sized RO systems, countertop filters and countless other commercial and residential water filter systems. Compliance with Prop: 65