SteriPEN Water Bottle Pre-filter
Works with SteriPEN Classic 3, SteriPEN Ultra, and SteriPEN Aqua. This pre-filter fits on Nalgene and other 32oz wide-mouth water bottles and filters particles and debris out of your water. To use, screw it onto your bottle and fill with water through the 40 micron screen. Remove the filter cartridge, insert your SteriPEN into the pre-filter, flip your bottle upside down and agitate until the SteriPEN (sold separately) indicates the treatment is complete. When you take the filter off, just make sure you wipe the rim of your bottle as this water may not have received treatment.
This product should last for a lifetime if you keep it clean.