Mammut Taiss Light Mid GTX £365

Mammut bills these as the lightest crampon-compatible mountaineering boots on the market. When it comes to weight, they even undercut the featherweight Arc’teryx Acrux LT. They use a similarly closefitting, foot-hugging last and a weight-conscious construction, combining synthetic uppers with a carbon fibre midsole plate and a Vibram Litebase sole unit. This reduces the sole thickness by 50% and weight by 30%.

However, it’s still fairly stiff, and the addition of a rear heel welt means they can be used with C2 semi-automatic crampons. The result is a very capable boot for technical terrain, with plenty of precision.

Edging performance is excellent, thanks to an asymmetric toe box and a flat ‘climbing zone’ for good contact grip on small pockets and ledges. The rest of the tread delivers reasonable traction, though the lugs aren’t the deepest. The boot also has offset lacing and an elasticated soft shell one-piece tongue, to help relieve pressure on the top of the foot. A stretchy gaiter at the heel helps to prevent snow and debris from getting in, while a Gore-Tex liner keeps feet dry. Lastly, a wraparound rand and TPU ‘exoskeleton’ adds rigidity, protection and abrasion resistance.

IF WE’RE BEING FUSSY

The close fit, unusually shaped toe box and offset lacing won’t suit all. Cushioning feels a little sparse, as they’re not really for big miles. They’re also expensive.

■ WEIGHT 700g (size 12)

■ UPPER Suede and Schoeller soft shell

■ MEMBRANE Gore-Tex

■ SOLE VIBRAM Litebase

■ MEN’S SIZES 6.5-12

■ WOMEN’S SIZE 4.5-8.5

Verdict

Unbelievably light, precise and nimble, these capable B2 boots excel on technical terrain. However, they’re a bit too specialist to be our first choice for UK winters.

“Very capable for technical terrain”