When the temperature plunges and conditions turn hostile, the 4-Piece Modular Sleeping Bag System is the sleep solution that doesn’t flinch. Engineered for extreme cold weather down to -15°C and inspired by military modular sleep systems, this four-component setup gives you the flexibility to adapt your insulation layer by layer — from cool nights to sub-zero expeditions. Use the patrol sleeping bag alone for mild conditions, add the intermediate sleeping bag for serious cold, and wrap the whole system in the waterproof bivy cover when wind, rain, and snow demand maximum protection. Everything compresses into the included compression stuff sack for efficient transport. Specifications Specification Detail System Type 4-Piece Modular Sleeping Bag System Temperature Rating Down to -15°C (combined use) Comfort Range 0°C to -10°C Outer Material Nylon Filling Synthetic Polyester Structure Multi-Layer Modular Bivy Cover Waterproof & Windproof Hood Adjustable Draft Collar Yes Closure Zipper Suitable Height Up to 1.8 m Occupancy 1 Person Storage Compression stuff sack included Why Choose This Modular Sleeping System? True -15°C Capability: When all four components are combined, this system handles extreme sub-zero conditions that single sleeping bags simply can’t match. Modular Flexibility: Use one, two, or all three sleeping layers depending on conditions — one system that adapts from cool autumn nights to harsh winter expeditions. Waterproof Bivy Cover: The outer shell blocks rain, wind, and moisture, keeping your inner layers dry even in wet conditions. Adjustable Hood & Draft Collar: Seals in body heat at the most vulnerable points — head and neck — for maximum thermal efficiency. Synthetic Fill in Damp Conditions: Polyester insulation retains warmth even when wet, unlike down which loses loft when moisture penetrates. I For Winter camping and sub-zero expeditions Mountain trekking and alpine adventures Military and tactical outdoor operations Survival and emergency preparedness kits Hunting, fishing, and cold-climate outdoor activities In the Box 1 × Waterproof Bivy Cover 1 × Patrol Sleeping Bag 1 × Intermediate Sleeping Bag 1 × Compression Stuff Sack