FWIW, I've been commuting in the same Ikea vest virtually every weekday since May. I found it plenty breathable over the summer, though admittedly my commute is in the morning and evening and we had a pretty mild summer here. My only complaint about it is the velcro fasteners sometimes don't keep it closed in windy conditions and can snag on clothing. Otherwise, it's great. The reflector stripes are 3M Scotchlite and do an excellent job reflecting light. I also like that the colors and pattern are pretty close to what road crews and traffic cops wear (at least around here), which I suspect does better drawing the attention and caution of motorists.