This whistle compass is a great tool and safety device for any backpackers, through hikers and day hikers. If you are in the Sierras where there's often little to no cell service, having an easily accessible compass and whistle is a great addition to your emergency toolkit. The whistle emits a loud, high-pitched sound and is attached to a durable breakaway lanyard. The compass is fluid-filled, which steadies the needle for a quick and accurate read. At 0.63 oz. is also lightweight and compact enough to take on any adventure.