I've been wearing Numi all winter and it makes such a difference not to have to wash sweaters between each wear because Numi keeps the pits protected! Best clothing purchase I ever made. I ordered more crop tops for summer because I did find it uncomfortable to wear a full extra layer in the heat, but I also wore the crops all winter under sweaters so they're versatile. Can't tell you how much peace of mind and effortless confidence these undershirts have given this sweaty Betty! I will say that the undershirts with unhemmed sleeves tend to roll up on the edge if under a tighter fitting shirt so there is some adjusting necessary, but that is minor compared to the benefit I've gotten.