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Mountain Equipment says:
A stripped back and highly breathable lightweight waterproof shell for the most exposed mountain running.
The Firefly uses the very lightest version of highly breathable 3-layer GORE-TEX Active 2.0 fabric in combination with a fast moving Active fit and our protective Mountain Hood, it’s a lightweight and highly packable shell you can rely on. A single chest pocket gives quick access to a phone or snacks.
Material & Construction