Whistles Ultralight & Loud Ultralight emergency whistle made Hilltop Packs for Apex Giant right here in Pennsylvania. There are two different versions. The single barrel we designed it to be as small and light as we could get it and still loud as possible. The double barrel adds more volume. Weights Single barrel whistle 0.12oz (3.6g) Double barrel whistle 0.24oz (6.8g) Sizes Both whistles are 2 inches long. Here are the exact specs. Single barrel whistle 0.45"x2.0"x0.35" Double barrel whistle 0.84"x2.0"x0.35" LOUDNESS Single Barrel - 127db Double Barrel - 132db CAUTION: Note on DB levels. All emergency whistles over 70db can cause damage to your ears.