Choosing the right insulation for a sleep system is one of the most important decisions for outdoor enthusiasts. Whether you’re bikepacking, alpine climbing, fastpacking, or heading out on multi-day expeditions, insulation determines warmth, weight, packability, durability, and performance in wet conditions.

Zenbivy has positioned itself at the forefront of insulation innovation by combining cutting-edge down technologies with advanced synthetic options. From untreated ultra-clean Muscovy down to next-generation ExpeDRY™ water-resistant down and high-performance Primaloft® synthetics, Zenbivy offers one of the most diverse insulation portfolios in the outdoor industry.

This comprehensive guide breaks down all Zenbivy down and insulation options, their technologies, advantages, trade-offs, and ideal use cases.

Understanding Fill Power (FP): Why 900FP and 950FP Matter

Fill Power (FP) measures how much volume one ounce of down occupies. Higher FP means:

• More warmth per gram

• Better compressibility

• Higher loft and insulation efficiency

900FP is considered premium high-end down, while 950FP+ represents elite, cutting-edge insulation found only in the highest quality down clusters. Zenbivy deliberately focuses on these high FP ranges to minimize weight while maximizing warmth.

1. Ultrasonic Muscovy™ 900FP (Untreated Grey Duck Down)

Ultrasonic Muscovy Down™ 90/10 grey duck down (untreated, additive-free)

Ultrasonic Muscovy™ is Zenbivy’s most natural and environmentally pure down option. It is completely untreated, preserving the down’s natural loft and avoiding performance loss caused by coatings or chemical finishes.

Key Technical Features

• 90/10 down-to-feather ratio

• True 900FP loft performance

• Untreated, additive-free down clusters

• Patented Ultrasonic Washing process

Ultrasonic Washing Technology

Zenbivy uses a patented ultrasonic cleaning process that:

• Exceeds industry cleanliness standards (IDFL)

• Produces ultra-clean, odor-free down

• Uses ~20% less water and energy due to fewer rinse cycles

• Reduces environmental impact compared to traditional washing

Performance Advantages

• Maximum natural loft

• Excellent compressibility and packability

• Long-term durability without chemical degradation

• Environmentally responsible processing

Trade-Offs

• No water-resistant treatment

• Loft can degrade faster in persistent humidity or condensation

Best for: Cold, dry alpine environments, ultralight purists who prioritize natural materials.

2. ExpeDRY™ Goose 900FP (PFAS-Free Water-Resistant Goose Down)

ExpeDRY™ water-resistant 90/10 goose down (PFAS-free)

ExpeDRY™ represents the next generation of water-resistant down technology. Unlike traditional DWR-treated downs, ExpeDRY™ is designed to be chemical-free and PFAS-free, addressing growing environmental concerns.

What Is ExpeDRY™?

ExpeDRY™ is a new water-resistant down technology developed by ALLIED Feather + Down. Instead of coating the down with permanent chemicals, ExpeDRY™ modifies the down’s structure to resist moisture while maintaining loft.

Key Benefits

• PFAS-free water resistance

• Faster drying time compared to untreated down

• Maintains loft better in humid conditions

• Minimal impact on compressibility and warmth

Why Goose Down?

Goose down is traditionally considered the gold standard due to its large clusters and high loft potential. ExpeDRY™ Goose combines this classic performance with modern moisture management.

Best for: Mixed-weather trips, damp alpine climates, long-distance trekking, users who want premium performance with improved wet-weather resilience.

3. ExpeDRY™ Muscovy 900FP (Water-Resistant Muscovy Down)

ExpeDRY™ water-resistant 90/10 Muscovy down (PFAS-free)

Zenbivy is the first outdoor brand to bring ExpeDRY™ Muscovy down to market, combining Muscovy’s unique biological advantages with next-gen water resistance.

Why Muscovy Down Is Special

Muscovy ducks produce some of the largest and most resilient down clusters in the industry. Their longer breeding period leads to:

• Larger plumes than many goose downs

• Higher loft potential

• Superior compression recovery

Performance Characteristics

Faster Compression Recovery

Muscovy down clusters are exceptionally resilient, meaning they rebound quickly after compression, maintaining loft over repeated packing cycles.

Bigger Plumes = Higher Loft

Mature Muscovy ducks produce large down clusters capable of achieving true 900+ fill power, rivaling elite goose down.

Stable Cluster Structure

Muscovy down has a natural “clinginess” similar to eider down. Clusters tend to interlock, reducing shifting inside baffles and improving insulation stability.

Ethical Free-Range Sourcing

Muscovy down is a byproduct of the food industry, but birds are typically raised free-range with access to water, unlike many industrial duck farms.

ExpeDRY™ + Muscovy = A New Benchmark

Combining Muscovy down with ExpeDRY™ technology delivers:

• Water resistance without PFAS

• Faster drying in humid conditions

• Better loft retention in condensation-prone environments

• All the natural performance benefits of Muscovy down

Best for: High-humidity environments, alpine bivy use, maritime climates, long expeditions where moisture management is critical.

4. 950FP Ultrasonic Muscovy Down™ (95/05 Grey Duck Down, Untreated)

950FP Ultrasonic Muscovy Down™ (95/05 grey duck down, additive-free)

This is Zenbivy’s pinnacle natural down insulation: ultra-high-loft Muscovy down without any chemical treatment.

Key Specifications

• 95/05 down-to-feather ratio

• 950FP+ loft potential

• Untreated, additive-free

• Ultrasonic washed for extreme cleanliness

Why Untreated Down Achieves Higher Fill Power

Chemical treatments can reduce loft by adding mass and altering cluster structure. Untreated down preserves:

• Maximum loft potential

• Natural elasticity of clusters

• Long-term performance without degradation

Performance Advantages

• Highest warmth-to-weight ratio

• Extreme compressibility

• Premium loft for expedition-grade warmth

Trade-Offs

• No water resistance

• Premium cost

• Requires good moisture management in the field

Best for: Ultralight alpine climbers, high-altitude expeditions, winter fastpacking, users who prioritize absolute performance per gram.

5. Primaloft® Gold 1-1001 Synthetic Insulation (Dual-Layer System)

Primaloft® Gold 1-1001 synthetic insulation (100gsm x 2 layers)

Synthetic insulation remains critical for users who operate in consistently wet conditions. Zenbivy integrates Primaloft® Gold, one of the most advanced synthetic insulations available.

Why Synthetic Still Matters

Unlike down, synthetic insulation:

• Retains warmth when fully wet

• Dries extremely quickly

• Requires less moisture management

Primaloft® Gold Advantages

• High thermal efficiency

• Soft, compressible structure

• Excellent durability

• Ideal for high-humidity environments

Dual-Layer 100gsm Construction

Zenbivy uses two 100gsm layers for:

• Better thermal uniformity

• Reduced cold spots

• Improved loft stability over time

Best for: Packrafting, bikepacking in wet climates, maritime expeditions, beginners who want low-maintenance insulation.

ExpeDRY™ vs Ultrasonic Muscovy™: A Philosophical Shift in Down Design

Zenbivy offers two distinct philosophies:

Ultrasonic Muscovy™ (Untreated)

• Maximum natural loft

• No additives

• Ultra-clean processing

• Best warmth-to-weight performance

ExpeDRY™ Treated Down

• PFAS-free water resistance

• Faster drying

• Better performance in humid environments

• Slight theoretical loft trade-off for real-world reliability

The choice depends on your environment and risk tolerance for moisture.

Sustainability and Ethical Sourcing

Zenbivy emphasizes sustainability across its insulation portfolio:

• Free-range Muscovy sourcing

• Down as a byproduct of the food industry

• Ultrasonic washing reduces water and energy use

• PFAS-free ExpeDRY™ technology avoids persistent environmental pollutants

This positions Zenbivy among the most forward-thinking brands in down ethics and processing.

Which Zenbivy Insulation Should You Choose?

Choose Ultrasonic Muscovy 900FP if:

• You want natural, untreated down

• You operate mostly in dry environments

• You want premium performance at a balanced cost

Choose ExpeDRY™ Goose 900FP if:

• You want classic goose down performance

• You need improved wet-weather reliability

• You prioritize PFAS-free water resistance

Choose ExpeDRY™ Muscovy 900FP if:

• You want the best balance of loft and moisture resistance

• You operate in alpine or maritime climates

• You want cutting-edge down innovation

Choose 950FP Ultrasonic Muscovy if:

• You want maximum warmth-to-weight performance

• You are building an ultralight expedition kit

• You are willing to manage moisture carefully

Choose Primaloft® Gold if:

• You expect consistent wet conditions

• You want low-maintenance insulation

• You prioritize reliability over absolute weight savings

Conclusion: Pioneering the Next Era of Down Innovation

Zenbivy is redefining how outdoor sleep systems are insulated. By pushing Muscovy down to 950FP+, introducing ExpeDRY™ water-resistant down without PFAS, and integrating elite synthetic insulation, the brand is shaping the future of outdoor comfort and performance.

Whether you are chasing 4000-meter summits, bikepacking through rainy mountain ranges, or building the lightest possible hiking kit, Zenbivy’s insulation lineup offers a tailored solution for every mission.

The next era of down innovation isn’t just about higher fill power—it’s about sustainability, real-world performance, and intelligent material engineering.