10 Best Sleeping Bag Liner For Warmth 2025 in the United States

The Sea to Summit Reactor Sleeping Bag Liner in Fleece Compact is designed to enhance the warmth and hygiene of any sleeping bag, making it a valuable addition for camping, hiking, and backpacking enthusiasts. Made from hollow-core Thermolite EcoMade fibers in a grid-pattern fleece, it efficiently retains heat, which is ideal for three-season use with a temperature rating of 32F and above.

The liner features a mummy shape for maximum thermal efficiency, shoulder zippers, and a drawcord footbox that can be opened or closed for personalized comfort. Additionally, the HeiQ Fresh odor control technology ensures the liner stays fresh even after extended use, which is a great plus for long trips. It is also compact and lightweight, weighing just 0.92 pounds and measuring 78 x 31.5 inches, making it easy to pack and carry.

However, while the thermal boost and odor control are beneficial, some users may find the polyester material less breathable compared to natural fibers. Also, its dark blue or black color options are limited. The product is backed by the Sea to Summit Guarantee, adding a layer of reliability. This sleeping bag liner is best suited for adults who need extra warmth and hygiene on their outdoor adventures.

The Sea to Summit Reactor Sleeping Bag Liner is designed to add extra warmth and hygiene to your sleeping setup. With its Thermolite Pro technology, it efficiently reflects your body heat, making it ideal for three-season use, with a temperature rating between 31 to 45 degrees Celsius.

The liner is made from Thermolite Pro and EcoMade Polyester, providing a good balance of warmth, comfort, and stretch due to its knitted fabric, making it flexible and comfortable to move around in. Its drawcord footbox is a practical feature that can be adjusted for comfort and fits well with certain Sea to Summit sleeping bags.

Additionally, the HeiQ Fresh odor control technology is a significant advantage for maintaining freshness during extended trips. The liner is lightweight, weighing just 0.67 pounds, and its compact size makes it easy to carry in your camping gear. However, while it offers good warmth, it may not be sufficient for extremely cold conditions. The bright yellow color might not be appealing to everyone, and though it is easy to care for, being made of synthetic materials, it may not offer the same natural feel as cotton or silk liners. This product is best suited for campers and hikers who need a reliable and easy-to-care-for sleeping bag liner for moderately cold conditions.

The Sea to Summit Silk Blend Sleeping Bag Liner is designed to add extra warmth and comfort to your sleeping bag, making it a great choice for campers who want a cozy, lightweight layer. Its material combines silk with hollow-core Thermolite Pro fibers, which trap heat efficiently thanks to special ceramic pigments that absorb infrared energy. This means it can help keep you warmer during cool nights without adding much weight—just about 0.33 pounds. The liner comes in a mummy shape with dimensions of 72" by 42", fitting most standard sleeping bags and supporting users up to 140 pounds comfortably.

One handy feature is the drawcord footbox, which you can open or close for extra ventilation or snugness, especially useful if you want to regulate your foot warmth. The liner also includes odor control technology, so it stays fresher longer, reducing the need for frequent washing. Its dimensions and weight make it compact and easy to pack, ideal for backpackers or campers looking to improve their sleep comfort without bulk.

This liner suits users seeking a lightweight, warm, and comfortable sleeping bag liner with some luxury feel, especially in mild to moderately cool conditions. Potential downsides include the higher price typical of Sea to Summit products and the possibility that it may not provide enough warmth for very cold weather camping. Also, those needing a liner for larger or heavier users might find the size or weight capacity limiting.