I looooove my smartwool arm warmers. Pretty much standard for me in temps in the upper 40s-50s. I'm planning on wearing them for my marathon this weekend - if I have to walk at the end and cool off, I can always pull them back up. If they get REALLY obnoxious on a long run, I take them off and hook them through my sports bra or knot them around my fuel belt/bottle holder.