Editor’s note: Welcome back to our series on sleeping bags- what goes into them, how they’re put together, and what you need to know about all of it. Check out part 1: Sleeping bag fabrics, part 2: Sleeping bag insulation, and then check back next week for the fourth and final installment. Additionally, our down vs. synthetic sleeping bags comparison is the ultimate guide to which bag is right for you.

Sleeping bags are complex systems. 

Fabrics, insulations, hardware and waterproofing treatments are mixed and matched in myriad ways. 

Good backpacking sleeping bags can cost anywhere from $100-$1,400, and we’ve created a guide to show you what exactly goes into every decision a manufacturer makes. Hopefully, you can use it to make informed decisions based on your budget and how you camp.

Today, we’re talking hardware and waterproofing—finishing touches that can make the difference between a great trip or a poor night’s sleep. 

Zippers

Zippers are one of the most mechanically stressed components on a sleeping bag, enduring thousands of cycles while being subjected to fabric snags, grit, moisture, and cold.

Coil zippers

Coil zippers are the standard on modern backpacking sleeping bags. 

• Composition: Continuous spiral of nylon or polyester monofilament
• Weight: Light
• Durability: Good; flexible, follows curves well, self-repairs minor tooth separations
• Cost: Low to moderate
• Common uses: Standard on most backpacking sleeping bags (main zip, foot vents)
• Pros: Lightweight, flexible, self-repairing, operates smoothly in cold temperatures
• Cons: Less durable than molded-tooth under high-tension use; ultralight variants have higher jam rate

Molded-tooth (vislon) zippers

Molded-tooth zippers use individual plastic teeth molded directly onto the tape. 

• Composition: Individual molded plastic or nylon teeth on woven tape
• Weight: Heavier than coil (by approximately 1 oz for equivalent full-bag length)
• Durability: Excellent
• Cost: Moderate
• Common uses: Expedition bags, guide-service bags, heavy commercial use
• Pros: Outstanding longevity, resistant to tooth separation
• Cons: Heavier, stiffer (harder to operate with cold hands or in the dark), does not self-repair

Cord, webbing, and hardware

The small components on a sleeping bag, including drawcords, cord locks, hang loops, and attachment points rarely get the attention they deserve. But, a frozen cord lock at 2 a.m. can ruin a night as surely as a poorly insulated bag.

Drawcords

Nylon cord

• Composition: Braided or twisted polyamide
• Weight: Light
• Durability: Good strength; UV sensitive
• Water absorption: Stretches when wet (can loosen hood tension overnight)
• Cost: Low
• Best use: General three-season bags

Polyester cord

• Composition: Braided or twisted polyester
• Weight: Lightweight
• Durability: Good; UV stable
• Water absorption: Minimal (maintains tension when wet)
• Cost: Low
• Best use: Bags where consistent cord tension matters; humid environments

Dyneema cord

• Composition: Ultra-high-molecular-weight polyethylene (UHMWPE)
• Weight: Extremely lightweight
• Durability: Exceptional strength; UV resistant
• Water absorption: Near zero
• Cost: High
• Best use: Ultralight and premium bags

Cord locks

Acetal (POM, Delrin)

• Composition: Acetal copolymer thermoplastic
• Weight: Minimal
• Durability: High stiffness and fatigue resistance; maintains mechanical properties in sub-freezing temperatures without embrittling
• Cost: Low
• Best use: Standard on nearly all backpacking sleeping bags; hood and collar adjustments
• Key consideration: Look for single-hand operation designs that can be worked with gloved or mittened hands

Storage and compression components

Stuff Sacks (compression)

• Composition: Siliconized nylon or ripstop polyester with nylon webbing compression straps
• Weight: Light to moderate
• Durability: Good; must withstand repeated compression cycles
• Cost: Low to moderate (usually included with bag)
• Best use: Field transport only; never for long-term storage

Storage Sacks

• Composition: Oversized cotton, mesh, or breathable synthetic
• Weight: Light
• Durability: Moderate
• Cost: Low (usually included with bag)
• Best use: Long-term home storage; allows insulation to remain lofted
• Key consideration: Storing a bag compressed in a stuff sack permanently damages insulation loft—always use the oversized storage sack or hang from a hook

Waterproofing and water-repellent technologies

A sleeping bag must manage moisture from two places: external condensation from above and body moisture from within. 

Thus, breathability is paramount.

Fluorocarbon DWR

Fluorocarbon-based DWR (durable water repellent) treatments provide the best-performing water repellency but are being phased out due to environmental and health concerns related to persistent fluorinated compounds (PFAS).

• Application: Factory-applied treatment to outer shell fabric
• Performance: Excellent water beading and oil repellency
• Durability: Longest-lasting DWR chemistry; degrades with use and washing but outlasts alternatives
• Environmental impact: Toxic and persistent; subject to state-level regulation
• Reapplication: Spray-on or wash-in fluorocarbon treatments available (for now)
• Status: Being phased out of new production; legacy bags still perform well

Non-fluorocarbon DWR

Non-fluorocarbon alternatives include silicone-based treatments, wax emulsions, and dendrimer polymer finishes. The performance gap with fluorocarbon DWR has narrowed significantly in recent years.

• Application: Factory-applied treatment to outer shell fabric
• Performance: Good water beading; diminished oil repellency compared to fluorocarbon
• Durability: Less durable than fluorocarbon DWR; requires more frequent reapplication
• Environmental impact: Considered safer for human health and environment
• Reapplication: Spray-on or wash-in treatments readily available
• Key consideration: For most backpackers, a well-applied non-fluorocarbon DWR provides adequate protection

Hydrophobic down treatments

While technically an insulation treatment, hydrophobic down intersects significantly with the waterproofing discussion. These treatments apply a DWR-like finish to individual down clusters.

• Application: Factory-applied to individual down clusters before bag construction
• Performance: Down resists moisture absorption and maintains loft in damp conditions; does not make the bag waterproof
• Durability: Good
• Cost: Adds approximately $30–$60 at retail
• Common uses: Premium down bags intended for variable or humid conditions
• Pros: Meaningful safety margin in damp conditions, faster drying than untreated down

Cons: Adds cost; a properly managed untreated down bag kept dry through good practices performs comparably