ST-FPWF Like the standard model The Frontier Pro™ is designed to trap 99.9% of harmful giardia, cryptosporidium, and other pathogens down to 2 microns in size, and is also anti-microbial. This model additionally includes a BiteMe™ Valve providing "no drip on demand flow", a draw tube for "direct from the source" drinking, a 28mm thread allowing for direct connection to standard water bottles and bladders, and a replaceable pre-filter (extras included). Filters up to 50 gallons. Color: olive drab and black. Weight: 2.5 ounces. Can be used in line with hydration bladders.