Terramar Helix Half-Zip Shirt

Works well when worn in conjunction with other layers. This is a base layer and when combined with short sleeved shirt underneath and rain shell or down on top, you'll be prepared for most situation

This is a base layer, but should not be confused with layers such as Under Armour necessarily. This is not skin tight, but does hug the body more than other layers may.  When I wear this with a shirt (perhaps on cooler mornings) or with a shirt and jacket (those 40 degree days), it works well. I am 5'9", 150 lbs. and a medium fits perfectly.

I used this on a recent trip to Glacier National Park. I wore it in the mornings with my down, but once lunch came around, it was closer to high 50s, low 60s.  I took my jacket off and just had a cotton shirt and my Helix; combined with my pack and constant hiking I was comfortable. 

The shirt also breathes well and scores high for me on its moisture-wicking capabilities. On that note, if it's breezy, you may chill off a bit more than you wanted. The Helix isn't waterproof and the water resistance is minimal, no more than you would really expect; it'll bead up, but then become saturated after time.

It has a little UPF protection (25 per their site). While it is thinner, it seems pretty well made it that it doesn't snag and leave holes or "hoop" out any of the material if snagged on bushes or logs.

I would not think again about getting another pair. This was a gift and once I looked up the price, it is very reasonable when it comes to the cost of other base layers of this kind.