Polartec and Big Agnes Launch Ultralight Sleeping Bag Liner with Alpha™ Next-to-Skin Insulation

March 6, 2026

Introducing the dreamiest sleeping bag liner yet

Planet Earth, The Universe (March 6^th, 2026) /OUTDOOR SPORTSWIRE/ – Polartec, a Milliken & Company brand and the premium creator of innovative and sustainable textile solutions, partners with Big Agnes, the Steamboat Springs, CO-based outdoor equipment pioneer, to launch the Alpha Direct Fleece Sleeping Bag Liner. The result is an ultralight thermal solution that provides five to ten degrees of additional warmth while maintaining exceptional airflow and packability.

Weighing just six ounces, the Alpha Direct Fleece Sleeping Bag Liner transforms the sleep system. Made from Polartec© Alpha™ active insulation, it functions as a temperature booster for three-season camping, a standalone piece for summer adventures, and a protective barrier that extends your sleeping bag’s lifespan. The liner compresses down small, making it an essential for space-conscious backpackers and bikepackers.

Polartec© Alpha™ changed the insulation game 13 years ago by engineering what the industry now calls active insulation. Unlike traditional insulators that trap heat and humidity, Alpha™ delivers dynamic thermal regulation, holding heat when needed and releasing it when it’s not. Lofted fibers and a mesh core create an ultra-breathable structure that actively resists moisture, dries rapidly, and delivers warmth without the weight.

“At Big Agnes, we’re focused on providing more comfort to backcountry adventurers,” said Bill Gamber, Big Agnes co-founder and president. “This lightweight liner weighs just six ounces (177g) and delivers incredible versatility for changing conditions. Whether you’re facing cold nights at altitude or desert heat, our Alpha Direct liner allows travelers to adapt their sleep system on the fly, extending comfort across a much wider temperature range.”

Sustainability drives the collaboration as much as performance. Polartec© Alpha™ utilizes 100% recycled content, and all Polartec fabrics carry Oeko-Tex® and Bluesign® certifications.

“Polartec© Alpha™ has consistently outperformed expectations across outdoor, military, and fashion applications for over a decade,” said Ramesh Kesh, Senior Vice President at Milliken & Company and Business Manager at Polartec. “This liner showcases the technology’s core strength: delivering consistent thermal comfort through superior breathability and adaptability, not bulk.”

The Big Agnes x Polartec Sleeping Bag Liner retails for $149.95, and is available now at bigagnes.com and select retailers.

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Polartec North American Media Contact:
Abigale Youcha, Akimbo Communications, abi@akimbopr.com

Big Agnes Media Contact:

Cade Michael, Backbone, cade.michael@backbone.media

About Polartec:
Polartec^®, a Milliken & Company brand, are a collective of curious minds, relentless innovators and dedicated problem solvers. We look beyond the existing and we create original. If it can be made, we will make it. And if it can’t? We’ll find a way. We are the originators and inventors of fleece. Our unique unrivalled innovations continue to lead and layer the future. Complete trust and authenticity are inherent in all our products, ultimately empowering people to concentrate on their moment, their activity and their unique experience in life without distractions. Our fabrics go beyond industry standards, with lightweight wicking and cooling, warmth and insulation, breathable weather protection, fire resistance, enhanced durability and more. Polartec products are used by performance, lifestyle, and workwear brands from around the world, the U.S. Military and allied militaries, and contract upholstery markets. For more information, please visit Polartec.com and follow Polartec on Instagram, Twitter, Facebook and LinkedIn.

About Big Agnes:

Named for a peak in the nearby Mt. Zirkel Wilderness, Big Agnes®, Inc. is located in Steamboat Springs, Colorado, and was founded there in 2001. The company produces award-winning sleeping bags, pads, tents, packs, insulated apparel, camp furniture and backpacks. For more information, visit www.bigagnes.com or call 1-877-554-8975.

©2025 Polartec, LLC. Polartec® is a registered trademark of MMI-IPCO, LLC.