Very high-quality fleece jacket, quite warm and lightweight! If you also have one of the MJC compatible jackets from Pentagon, it enhances it perfectly for colder situations. Regarding size and fit, for 1.75m and 76kg I got the SMALL and it’s just fine. Neither tight nor big. You can, just barely though, wear a thick sweatshirt underneath. For comparison, it has about the same fit as a similar fleece in LARGE from Decathlon. Based on the fit of the SMALL, I think the MEDIUM would be quite comfortable.
*Updating... The SMALL, after 2 washes, has become tighter, you need to wear it several times for it to loosen up. Therefore, the MEDIUM is a better choice for anyone who wants to wear it as a jacket. However, for anyone intending it mainly for use as an inner lining, the SMALL fits better with a MEDIUM softshell.

At first glance, it looks nice and warm; I would suggest one size bigger to make it more comfortable and to pair it with a hoodie.

Incredible, words are unnecessary. Since I bought it, I haven't caught a cold outside again. Truly very warm, convenient, and I have tested it in very low temperatures. I highly recommend it, it is clearly worth its money. I have had it for almost two years. Get it.

I recently bought it due to a trip to Geneva.
It was worn as a jacket, under the main coat, which was a softshell and had short sleeves, without thermal or thermal underwear.
I faced temperatures from -2 with snow, to 4-5 degrees Celsius with rain.
I didn't feel anything on my body, in fact, I even sweated at times.
It is very soft, perfectly hugs the body and keeps it perfectly warm. It has a strange hydrophobic character, as water does not absorb, but stays on the surface and easily shakes off. I compare it to a simple Columbia fleece (which costs twice as much) and I have to admit that the Athos is a real beast that will always stand up to the cold and strong wind.
It has a double zipper, which I must note requires some extra attention as it is particularly hard (I imagine it is so for heat preservation and not due to a flaw) when zipping up.
I would buy it again and again. Congratulations to Pentagon for this gem!

Thick, very good quality fleece with a high collar that covers the neck.. a real beast.. I took it out of the washing machine almost dry and I was speechless.. for testing, I let it dry inside the house to see how quickly it dries.. it is indeed as the description says..