Baselayer (Layer 1) Long-sleeve wool or synthetic top. Quarter zip styles will allow for better temperature regulation. We recommend light colors, which best reflect the intense sun on hot days. What Works This is the first layer of your system. Long sleeves are mandatory on the summit climb and upper mountain to protect your skin against abrasions should you slip or need to self arrest. This should be a quick drying, fast wicking, non-cotton, and comfortable top.