S3 Foam Filter Bottle 20-ozEnjoy safe, clean water anywhere in the world with Sawyer Select Water Filters and Purifiers which remove virtually all contaminants found in fresh water while also improving taste and odour. Available in three models, these systems combine a proprietary foam membrane in an durable silicone bottle with our 0. 1 micron hollow fibre filter at the top ensuring access to clean water in the back country, while you travel, at the office, or for emergencies.