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Six Moon Designs says:
An umbrella is one of the most versatile pieces of gear you can own. It offers a shield from the rain, shade from the sun, can act as a micro-shelter, and even be used as an anchor point for your tarp or tent. The Rain Walker SUL does all of that at a mere 5.5 ounces.
The Rain Walker SUL is a great alternative to traditional rain gear, especially in hot and humid climates. An ultralight umbrella allows you to dress for the temperature instead of the weather. And in rainy conditions, you have a great mini shelter for checking maps and guidebooks or even snapping pictures.