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Synthetic Insulation Guide

Whether you’re looking for a light jacket to wear around a campfire, or a reliable barrier from nasty mountain conditions, Montbell’s synthetic insulated garments provide versatile warmth for your active outdoor passions.
We put together this guide to help you educate yourself on the need-to-know aspects of synthetic insulation so that you can select the best piece for your next adventure.

Though somewhat heavier than their down counterparts, garments that use synthetic insulation have distinct advantages that are relevant for both casual dog walks and multi-month treks across countries. First and foremost, synthetics can insulate when wet and dry quickly thanks to the water-repellant properties built into their fibers. This makes them an excellent choice for exploits in locations where moisture is abundant and hard to get rid of. Synthetics are also easier on the wallet, are hypo-allergenic, and offer better breathability than comparable down options. Such breathability reduces the frequency of those annoying layer-shedding stops when hiking uphill or ski touring, since a light synthetic layer donned at the trailhead will vent sweat and body heat as the going gets tough. If any or all of these advantages sound appealing, then a synthetic insulated garment might be right for you.

Whether you’re considering a quality option from Montbell, or another manufacturer, knowing how to compare the relative warmth of synthetic garments is key to making an informed purchasing decision. It all comes down to the number measured in g/m² (grams per square meter) that you’ll find in the garment’s specifications:

The higher the number, the warmer the insulation.

For example, a garment with 120 g/m² of insulation will be warmer than one with 60 g/m² or 40 g/m² and so on. It’s as simple as that.

However, keep in mind that this does not state which warmth level is right for you. Depending on body type, activity level, and weather, the UL Thermawrap’s 40g/m² could be perfect for one person and the Thermawrap Classic’s 60 g/m² could be best for another on the same autumn hike.

At Montbell, when we can’t find the materials or technology to exceed our standards for quality and value, we roll up our sleeves and invent them ourselves.

Exceloft is Montbell’s proprietary synthetic insulation designed for peak performance and incredible comfort. Exceloft utilizes three different proprietary fibers, one to maintain loft, one to trap warmth, and one to bridge the gap between the two. This trio works together to provide you with dependable loft and breathable warmth on every adventure.

Ultimate heat retention

Compared to some synthetic insulations of equal weight, EXCELOFT® achieves the highest Clo Value (a measurement of thermal insulation).

Extreme Resilience

EXCELOFT® is highly packable, while maintaining loft after repeated compression cycles.

Quick Drying Ability

EXCELOFT® maintains thermal properties by utilizing hydrophobic silicone impregnated fibers that retain less than 1% of their weight in water when wet.

Our thinnest level of insulation. Purpose built for providing a touch of warmth during active use in cool weather. Excellent for layering.

UL Thermawrap Series

Ultralight insulation for moments in motion. As the most breathable insulated pieces we’ve ever made, the UL Thermawrap series are purpose built to provide light, air-permeable warmth that moves with you during high-octane activity. Offered in three configurations to marry perfectly into your layering family. Cut for an athletic fit.

Insulation that weighs less than a traditional sweater or fleece but is just as warm.

Thermawrap Classic

Quick-drying sweater-weight warmth that is highly wind resistant and features smooth face fabric to allow for easy layering over the jacket. Cut for a casual fit to accommodate layers underneath.

Thermawrap Skirt

Ideal for lounging in front of the fire in an alpine hut trip, this versatile insulated, reversible skirt is sure to be a conversation starter.

Warmer than sweater weight garments, mid-weight jackets and parkas perform wonderfully in cold weather as stand-alone outer jackets, or as part of a layering system in severe conditions.


An ample fill of Exceloft insulation is wrapped with a durable 40-denier face fabric that features an additional wind-shedding layer. The result? An insulation piece that helps keep in warmth, keep out cold winds, and most important of all, keep you comfortable while on the trail and back in town.

Thermawrap Pro

Based on our Thermawarp Classic, the Pro features more insulation for increased warmth, 20-deinier face fabric for added durability, and a hood for maximum protection from the elements. Features a casual fit to accommodate layers underneath.

Thermawrap Parka, Vest

Within our mid weight lineup, the Thermawrap series features the highest insulation fill in the core area and the lightest face fabric, delivering excellent performance and comfort in the cool temps of autumn or spring, and for layering in winter.

TEC Thermawrap Pants

The Tec Thermawrap Pants are engineered with serious mountaineers in mind, but often satisfy the unique needs of cold weather backpackers and active mountain town dwellers.

The warmest synthetic options, heavy weight garments are for when conditions demand warmth and protection from the elements.

Flatiron Parka

Our warmest synthetic insulated option utilizing 120 g/m² of insulation to keep your core warm while 80 g/m² in the sleeves make sure you don't overheat. The DRY-TEC outer shell helps keep you dry and features like a helmet compatible hood and 2-way zipper make this an excellent choice as a belay jacket.