The Burton Synthetic Midweight Base Layer Long Neck top pairs HeiQ Smart Temp thermoregulation with a slim, four-way stretch fit built for easy layering under a shell. The extended neck doubles as a built-in neck warmer when the weather turns, so the top adjusts to effort and conditions without adding bulk. What Our Gearhead(R) Experts Are Saying:"I've worn this three days straight on back-to-back tours without a wash, and HeiQ Fresh actually keeps it from turning into the usual synthetic funk by day two. The four-way stretch never binds under a shell even reaching overhead to plant a pole."