Unused Montbell water filter, released this year. By attaching it to a separately sold Montbell flex water pack (1L-2L) or a commercially available PET bottle (∅28mm opening), you can secure drinking water even outdoors. I am selling it because my usage schedule has been postponed. Immediate purchase is OK. Returns are not accepted. Please refrain from price negotiations. High-performance water filter that removes 99.9999% of bacteria. - Brand: mont-bell - Product name: Water Filter - Filter performance: 99.9999% bacteria removal - Accessories: Cleaning adapter