Through Dark Mantra Fleece Review: A Premium Hiking Mid Layer Tested

Introduction

The Through Dark Mantra fleece is a premium mid layer built around a thick Polartec Thermal Pro pile fabric and a compact 425 g weight. It comes from Through Dark, a brand formed by former UK special forces personnel with the aim of producing some of the best outdoor clothing and equipment on the market.

The result is a fleece that prioritises warmth, breathability and a close, draught-free fit rather than a low price. It sells for around £195, which puts it firmly at the top end of the hiking fleece market, and the brand’s own mantra, endeavour through adversity, sets the tone for what it is trying to be.

For anyone who has spent a long day on a hillside, the appeal is easy to understand. You pull it on and the warmth arrives immediately, and the fabric keeps working while you move rather than turning into a sweat trap.

Who This Fleece Is For

This is a mid layer for hikers, backpackers and wild campers who feel the cold and want a warm layer that stays comfortable during steady effort. Its high warmth to weight ratio makes it a strong candidate for cold-weather trips where every gram in the pack matters.

It also works as an outer layer in calm, dry conditions, particularly around camp in the evening. It is less suited to riders of cold cutting wind, where a windproof shell over the top makes far more sense.

Main Strengths: Warmth, Weight, and Fabric

The headline strength is the warmth to weight ratio. At 425 g, the Mantra delivers a thick pile that feels instantly snuggly, and Through Dark rates it 10 out of 10 for thermal performance. That combination of low weight and high loft is exactly what makes a mid layer useful on a long ascent.

Breathability is the second standout. Despite the deep pile, the fabric is rated 8 out of 10 and it genuinely does not leave you overheating or clammy underneath, which is unusual for a fleece this warm. The material is also fast drying and anti-pilling, so it resists the scruffy surface that cheaper fleeces develop over a season of use.

Storage is generous for a layer of this type. There are two zippered hand-warmer pockets, a chest pocket up top, and two internal dump pockets, so the Mantra carries a surprising amount of kit when it is worn as a mid layer or an outer layer around camp.

Fit, Sizing, and Draft Protection

The cut is deliberately generous in the body. In a size small on a 5 ft 8 in, 70 kg frame, the hem sits neatly over the backside, which is a genuinely useful detail because it stops cold air creeping in at the waist when you bend or reach.

Through Dark has also paid attention to the openings. Elasticated hem, elasticated cuffs and a high, thick collar all work together to seal the gaps where cold air normally gets into a layering system. Thumb loops are a welcome addition for pulling the sleeves down over your hands on a cold morning.

Things to Consider Before Buying

Wind resistance is the honest limitation. Through Dark rates the fabric 6 out of 10, and while the Mantra holds off more wind than many fleeces, it is not a wind blocker. Worn as an outer layer in a cold cutting wind, air will pass through the fabric, so pair it with a shell when conditions turn exposed.

Durability is the second trade-off. The brand rates it 4 out of 10, which reflects the reality of pile fleece: rub it against rock and you can expect holes. Treat it as a mid layer rather than armour and it will hold up well.

Price is the third consideration. At around £195, this costs many times more than the fleeces most people pick up on a whim, and that gap is the single biggest reason to think carefully before buying.

Care, Durability, and Long-Term Value

The fabric’s anti-pilling finish and fast drying behaviour both work in its favour over time, and the construction feels like something that will last many months and years if it is looked after properly. Wash it sensibly, keep it away from abrasive rock, and the pile should stay lofty.

That long service life is part of how a premium fleece justifies itself. A cheap fleece that flattens and pills after a season is not really cheaper if you replace it twice as often.

Buying Advice

Buy the Through Dark Mantra if warmth to weight, breathability and a draught-free fit matter more to you than price. It suits cold-weather hikers and backpackers who want one mid layer they can rely on for years, and the pocket layout means it can double as a camp layer without extra pouches.

If your trips are mostly windy and exposed, spend part of the budget on a windproof shell instead, because no fleece in this class will stop a cutting wind on its own. If you simply need a warm layer for gentle walks, a lower-cost fleece plus a shell will cover the same ground for far less.

Either way, the Mantra is a clear example of what the top of the hiking fleece market looks like: exceptional fabric performance, thoughtful detailing, and a price that reflects both.

Conclusion

The Through Dark Mantra fleece earns its premium positioning through fabric and fit rather than branding. Its 425 g weight, thick Polartec Thermal Pro pile and 10 out of 10 thermal rating deliver immediate warmth, while the breathable, fast drying, anti-pilling fabric keeps it comfortable on the move.

The trade-offs are equally clear: it is not windproof, the pile can be damaged by abrasion, and at around £195 it is expensive for a fleece. For hikers who want a warm, breathable, well-sealed mid layer that should serve for years, it is a compelling choice. For everyone else, a windproof shell and a cheaper fleece will get the job done.