SOLD IN CASE QUANTITES ONLY Green Coconut Carbon Filters are the carbon block pre-filter that will reduce chlorine, organic chemicals, mercury, lead, PBCs, sulfur and heavy metals. #741604 is 20 in x 4.5 in. #728845 is 20 in x 2.5 in. #741646 is 10 in x 2.5 in. #741656 is 20 in x 2.75 in.