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Fox 40 Micro Whistle vs Petzl Sm'D Twist-Lock Carabiner
Weight and specs compared for 2026 — and which one to choose.
Fox 40 Micro Whistle is the lighter option — 41 g lighter than the Petzl Sm'D Twist-Lock Carabiner (80% less weight). If grams matter to you, that is the one to beat.
Petzl Sm'D Twist-Lock Carabiner
51 g
Lightweight aluminum D-shaped locking carabiner with twist-lock gate, 23 kN major axis, certified CE EN 12275 and UIAA.
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Fox 40 Micro Whistle vs Petzl Sm'D Twist-Lock Carabiner: which should you buy?
If saving weight is your priority, the Fox 40 Micro Whistle wins — at 10 g it is 41 g (80%) lighter than the Petzl Sm'D Twist-Lock Carabiner (51 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.