Carry the Frontier filter as a back up on multi-day backpacking trips in case larger pump filters clog or become damaged.

携带Frontier过滤器可作为多天背包旅行的备用，用于大型泵式过滤器阻塞或损坏后。

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Carry the Frontier filter as a back up on multi-day backpacking trips in case larger pump filters clog or become damaged.

携带Frontier过滤器可作为多天背包旅行的备用，用于大型泵式过滤器阻塞或损坏后。

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