I have the heavier weight Smartwool Merino 250 gaiter and found it so useful for winter hiking/snowshoeing that I decided to get the Merino 150 as well, for use in slightly warmer temps. This Merino 150 works the same way, but seems a bit longer and looser, so I fold it down quite a bit unless I'm trying to cover my mouth and nose. I would use this 150 in temps above 35 degrees for non-biking winter activities and 40-50 degrees if cycling. With a hat on, the 250 weight kicks butt in keeping my neck warm, enough so that I rarely need to use a hood while hiking or snowshoeing, which allows better hearing and peripheral vision when temps are <35 degrees, down to the the single digits. I haven't had a chance to use either the 150 or the 250 for cycling, but would not have a problem with either one when it's cold.