Looking like a retro-down jacket dating back to the 1970s this new offering from TNF makes some big claims. The blurb states that the man-made Thermoball fibres, actually small round clusters, trap enough heat to offer the warmth of down, together with down’s compressibility, light weight, and loft. Plus the performance of synthetic fibres when in wet conditions.

I can endorse the jacket’s lightweight and compressibility claims: it weighs next to nothing (330g (m); 285g(w)) and it sure can be stuffed into a small space; both of which are great advantages when day tripping or just wanting to keep the weight and bulk down.

It was so easy to whip out of a small pocket, flick out and pull on – nice work TNF. When it comes to heat retention and wind proofing, I was quite surprised. I took the Thermoball on a few trips, day excursions, into the hills at dawn, and warily left behind my normal shell jacket. So when it was time to don some extra cover I was pleased the jacket did offer both excellent warmth and wind protection. Both times it was pre-dawn on the tops and quite windy. I was very sweating from a rapid uphill trek and quickly starting to cool – times when you rely on being able to shrug into a good warm jacket. The Thermoball didn’t disappoint.

It was also a good performer when wet. I tried it out over a couple of days in a big southerly blow in Canterbury. I was wearing it during intermittent exposure to the rain and found that, though quite wet, it still kept me warm.

The Thermoball is comfortable to wear and feels just like a small down jacket, which is very pleasing, though some may not like the styling with the use of numerous small panels (rectangles and squares) which keep the insulation in place. There are just two waist pockets, a full length zip, and a high collar but no hood – so TNF has kept it simple, which for me is part of the appeal of this jacket.

A basic, but eminently serviceable heat trap.