"Thunderstorms and intense rain are coming at eleven, so we will start at three in the morning," I announce to my running expedition participants and tell them to bring a good jacket.

Tomorrow we are going to Musala, which is not only the highest mountain in the Balkans, but also the highest peak of the Bulgarian Rila mountain range. We are at the end of the Balkan's Highest Peaks expedition, in which we climb the 7 highest hills of 8 different countries in 12 days, and Musala is the penultimate piece of this puzzle. We only have one chance and we can't afford to miss it. Speed and ease are the keys to success in our case. The Endorphia jacket is ideal for such a scenario, and luckily I have it with me and am looking forward to putting it to the full test.

Musala, 2925 metres

I'm one of those people who don't like to hike or run heavy and I'd rather cut a little bit from my comfort than to have to carry extra pounds. Perhaps that's what led me to choose mountain crossings and expeditions that don't require me to carry an equivalent of a small car on my back as an Expedition Club guide. As a father of two kids, I don't have the space to take on more time-consuming projects, so I left the heavy backpack in a corner for a few years and focused on short, but all the more intense, forays into the mountains. To that end, I also choose all equipment that one can rely on. I've been testing the Tilak Endorphia jacket for the last six months, and have had the opportunity to try it out in a wide variety of conditions - whether during a summer rain on the long-distance GR11 route...

....or intense wind near Chamonix...

...but also on my daily trail runs in the beautiful, wintery Czech landscape.

The Endorphia jacket is made of GORE-TEX® Infinium™ double-layer membrane material, offering an excellent combination of wind and water protection. However, it still retains high vapour permeability. This means that it not only protects you in bad weather, but also won't let you drown in your own sweat during heavy physical exertion. Of course, you'll find a waterproof zipper, taped seams, anatomically shaped sleeves, one-touch hood drawcord or extended back.

Pleasing is also the possibility to pack the jacket into one of the two outer pockets.

The weight is especially surprising - just 198 grams (in size L) is really great and makes it an ideal choice for activities such as trail running or fast movement in the mountains.

A comparison with the Tilak Aira non-membrane jacket comes to mind. The latter is 60 grams lighter, but not fully wind and waterproof. It is only suitable for fog or light rain (it has a permanent DWR treatment). The material used in the Tilak Aira is called Pertex Quantum Air. It offers higher breathability, ideal for intense activities in milder conditions. The Endorphia is made of Gore-Tex Infinium and has this parameter slightly lower. However, it is still excellent and provides sufficient protection against inclement weather. For example, compared to the flagship Tilak Evolution, the Endorphia has more than twice the breathability. Thermal comfort is also an important parameter. One packs the Aira as a backup windbreaker "just in case" and is designed for activities where a lot of heat is generated. This makes it more suitable for milder temperatures - ideally for spring and autumn.

The Endorphia is a bit heavier, but provides the perks of a membrane jacket and can be a perfect choice for active winter sports.

It is still true that you have to remain physically active, but you can take more wind and you don't need to shy away from snow or medium rain. Although it is still a very lightweight solution, one can rely on it and, in my opinion, it offers the ideal balance of weight and comfort. Overall, the Tilak Endorphia is an example of what a modern outdoor jacket for faster paced sporting activities should look like - it's lightweight, durable and thought out to the last detail. If you're looking for a reliable companion for the mountains (optimally for running), it's definitely worth considering. A great choice for winter active movement in the Czech forests and woods, offering ideal comfort balancing on the edge of minimalism.