This was my first SPF t-shirt and I was pleasantly surprised. Wore it on two hikes this week and it felt great. The scorching Colorado sun didn't break through. It also seemed to repel mosquitoes. It wasn't hot during the long climb up the mountain. In fact, I think I'd be warmer in a t-shirt, although I'd have to do a parallel test to be sure. I wish I had bought something like this ten years ago. The only downsides are that it needs to be machine washed on a gentle cycle or by hand and the sleeves can be an inch longer so there's no tension when you put your thumbs through the thumbholes. However, the shirt is stretchy, so it works. The sun is no joke. Skin cancer (and aging skin) is no joke. Protect yourself!