





BOOST 4 — More Warmth, More Adventure When the night gets colder than expected, BOOST 4 has your back — and your feet. This featherlight footbox li...
Choose options






BOOST 4 — More Warmth, More Adventure
When the night gets colder than expected, BOOST 4 has your back — and your feet. This featherlight footbox liner, weighing just 90 grams, boosts the limit temperature of any sleeping bag by a remarkable 4°C, giving you the warmth and confidence to push further into the unknown.
Built with a tough rip-stop shell and lining, BOOST 4 shrugs off the rigors of the trail without sacrificing comfort. The easy-to-adjust draw cord with a sewn-in cord stopper lets you seal in precious warmth in seconds, even with frozen fingers. Every detail is designed for those who chase horizons: crafted from 100% recycled fabrics and filled with RDS-certified European Duck Down, it offers uncompromising performance with a lighter footprint on the world you love to explore.
On warm summer nights, trust your sleeping bag alone. But when the air grows thin and the temperature dips, add BOOST 4 and stay out longer, dream deeper, and wake up stronger. Because adventure shouldn't stop when the cold sets in — it should only get better.
• Boosts the limit temperature of any sleeping bag by 4°C
• Tough rip-stop shell and lining
• Draw cord with sewn-in cord stopper for easy adjustment
• Made of 100% recycled fabrics
• Filled with RDS-certified European Duck Down
• PFAS-free
Length
40 cmFoot widthDefault Title: 51 cm
Official weight
90 g
Total weight120 g
ShellFabric Name: 20D Nylon, rip-stop, 41 g/sqm, 100% recycled, PFAS-free
Fabric Composition: 100% polyamide (recycled)
Fabric Construction: 41g/sqm, 20D*20D, 223T*185T
Fabric Weight: 41 g/m²
Yarn thickness: 20D*20D
Thread count: 223T*185T
LiningFabric Name: 20D Nylon, rip-stop, 41 g/sqm, 100% recycled, PFAS-free
Fabric Composition: 100% polyamide (recycled)
Fabric Construction: 41g/sqm, 20D*20D, 223T*185T
Fabric Weight: 41 g/m²
Yarn thickness: 20D*20D
Thread count: 223T*185T
Filling Name: Crystal down
Filling Type: Crystal Down® European Grey Duck Down, 90/10 600+ cuin, RDS-certified
Mixing Ratio: Crystal Down® 90/10 600+ European grey duck down
Fill Power (EU): 600+ cuin
Fill Power (US): 650+ cuin
Pack Type: Pack sack
Pack Diameter: 8 cm
Pack Length: 15 cm
Compressed Pack Diameter: 7 cm
Compressed Pack Length: 12 cm
Every Nordisk product is designed in Denmark with a focus on functionality, durability and materials that hold up season after season. Our tents, sleeping bags, down jackets and gear are developed with 125 years of outdoor expertise as their foundation — and with the same starting point every time: good gear should last.
Accidents happen. If your Nordisk equipment is damaged in an unforeseen accident, our Beyond Repair Guarantee offers you 50% off a replacement product. Because an accident should never stop you.
Not every incident requires a new product. Nordisk's Care & Repair programme offers professional repair of sleeping bags and zippers, washing and re-lofting of down products and much more. The best solution for your gear — and for nature.