The Outdoor Research Astroman shirt is made from a very stretchy recycled nylon blend fabric that fits more closely than the other shirts tested. The stretch means it still gives unrestricted movement.

It does have a slightly clingy feel but I didn’t find this very noticeable in use. The fabric is soft and feels comfortable next to the skin. It has a 30-50+ UPF rating. The variation is because the UPF is reduced when the fabric is stretched. The fabric is breathable and comfortable in the heat. To increase the comfort there’s a wicking mesh panel on the back yoke. I can’t say I noticed this makes any significant difference in what counts as hot weather in the Scottish Highlands, but it might in much hotter places. This is covered when wearing a rucksack.

The shirt closes with studs, which I prefer for ease of use over buttons. The cuffs are stud-closed too. Rolling the sleeves up is easy, but there’s no strap and loop, or buttons to keep them in place. There’s a stud closure on the tiny pocket as well. The pocket is too small to hold much though. My smartphone will fit in but so much pokes out of the top that it’s not secure. You could fit a small tube of sunscreen or insect repellent in but that’s about it. The hem is curved and stays in trousers well when you stretch. Overall the shirt fits well.

As a shirt for hot weather the Astroman works well, as long as you don’t want pockets and you like stretchy fabric – I prefer loose-fitting shirts but that’s a personal choice. The Astroman is expensive compared with alternatives.

How Chris tested

Chris is 5’8” and wears a size large. He tested these shirts in warm weather from spring into early autumn on high and low level walks in the Scottish Highlands. The shirts were weighed on his own scales.

This review was first published in the April 2026 issue of The Great Outdoors.