Lightweight Extension for the Helium UL Bivy The Helium UL Vestibule is built as a lightweight, waterproof extension for the Helium UL Bivy, adding extra storage and weather protection for fast-moving backpackers and minimalist adventurers. Crafted from 100% nylon 15D ripstop with a silicone coating, this semi-translucent vestibule delivers durable, waterproof performance while keeping weight to a minimum. The barrel attachment system integrates seamlessly with the Helium UL Bivy for a secure, reliable setup. Reflective logos and trims improve low-light visibility, and two included aluminum stakes with stake loops provide stability. Designed for use with a single trekking pole, it offers compact, efficient gear storage and weather protection without added bulk. Note: Compatible only with the Helium UL Bivy.