Fox 40 Micro Whistle vs SOL Escape Bivvy

Weight and specs compared for 2026 — and which one to choose.

Fox 40 Micro Whistle is the lighter option — 132 g lighter than the SOL Escape Bivvy (93% less weight). If grams matter to you, that is the one to beat.

Spec	Fox 40 Micro Whistle	SOL Escape Bivvy
Weight	10 g · 0.010 kg · 0.02 lb	142 g · 0.142 kg · 0.31 lb
Brand	Fox 40	SOL
Category	Safety	Safety

Fox 40 Micro Whistle

10 g

Pealess safety whistle audible up to 1km.

Full details →

SOL Escape Bivvy

142 g

Breathable emergency bivvy bag. Reflects 70% of body heat.

Full details →

Fox 40 Micro Whistle vs SOL Escape Bivvy: which should you buy?

If saving weight is your priority, the Fox 40 Micro Whistle wins — at 10 g it is 132 g (93%) lighter than the SOL Escape Bivvy (142 g). That said, the heavier option may justify the extra grams with more capacity, durability or comfort, so weigh the trade-off against how you'll use it.

See where both rank against everything else in this category on the lightest safety page, or browse the full gear weight database.

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