The freshly redesigned REI Lightweight Polartec Power Dry Half-Zip top needs a fresh new shorter name, but other than that it's a perfect piece of topper. We've used the prior design on Denali twice and love it. The newbie is going up shortly for its breaking in.
The LPPDHZT (seriously?) uses two different yarns, one inside optimized for wicking and one outside optimized for drying quickly. The UPF 20 protection is perfect for hanging out on the glacier, and when the tough get going the zipper starts opening, for venting sure, but also to show off our bony white chest: stop it ladies, there's enough to go around!
The flat seams let you grunt along under a Denali-class load monster, and the light gray color option is appreciated to prevent the dreaded heat-sink phenomenon. At a mere 6.4 ounces for a men's medium the LPPDHZT is thin and light enough to carry an extra for expedition use. Highly recommended. Note the official description mentions a zipper flap, but that's apparently a marketeer smoking the wrong end of the crack pipe. Again.