Rab Mythic Ultra £380

+ Amazing warmth-to-weight ratio, supremely warm, highly technical

- Expensive, overkill for milder days, flimsy shell, quite bulky

Billed by Rab as the “ultimate ultralight down jacket for freezing temperatures”, the Mythic Ultra is a very warm and thickly-lofted puffy jacket with a technical design.

The warmth-to-weight ratio is superb, courtesy of the 240g of premium 900 fill power down, while the TILT inner – Rab’s heat reflective technology – improves thermal efficiency further. Yet despite all of this plush insulation, the jacket somehow isn’t too boxy or chunky, and instead has an athletic and technical feel.

The Pertex Quantum outer is soft, windproof and ultralight, but the 10-denier material does feel rather thin and flimsy. First-rate features include a nicely-shaped adjustable hood with small peak, adjustable waist hem with dropped cut for good coverage over the groin and backside, one external chest pocket, two hand-warmer pockets, and elasticated wrist cuffs for sealing out the cold.

In terms of baffle construction, stitchthrough baffles on the arms and hood give better mobility, while offset boxwall baffles around the core encourage the down to fully loft and spread evenly, thus maximising heat trapping. The jacket is too warm for milder conditions and too thick for layering, but for wintry days it is a super-cosy and high-quality jacket with uncompromising performance.

■ Men’s sizes S-XXL ■ Women’s sizes 8-16 ■ Weight 487g (men’s medium) ■ Insulation Nikwax hydrophobic European goose down

(900 fill power)