Sierra cups have been overtaken to a large extent by better technology, as well as the declining practice of dipping a cup into "pristine" mountain springs and streams.

I have a setup in which a Sierra cup (with folding handle))contains a small esbit holder, some cubes, matches, and the ever essential tea bags - nice and light and guarantees that nice cup of tea wherever.

The vertical walled units that fit around a Nalgene water container are actually more practical and they make perfectly fine tea as well.

Plenty of S. cups available from REI and other suppliers.
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Geezer in Chief