Instructables user dilg writes:

Merino wool is an excellent material for cool weather outdoor wear because it is lightweight, moisture-wicking, and still holds its insulating properties when wet. Unlike other wools, Merino isn’t “scratchy” on the skin and is relatively hard-wearing if knit properly, withstanding even washing machine treatment.

This Instructable illustrates how to add a 12in zipper to a sweater, useful for regulating your body’s temperature when cycling or hiking. A similar zipper sweater from Ibex for example retails for $75-105. I made this one from a thrift store sweater and zipper for less than $10.