MSR MiniWorks EX Microfilter for $59.99 shipped. Here is a screenshot for your reference. Alternatively, it is available at REI for $59.99 shipped. It features eramic/carbon Marathon EX element that removes bacteria, protozoa and unpleasant tastes and odors caused by organic compounds, such as iodine, chlorine and pesticides. This filter can be cleaned over and over for maximum field life with no tools required. Most places have it for about $89.