Vests. It’s almost like they’re not even there. Yet, when they are there, they can protect your core from the effects of wind, early morning and late afternoon cold, and precipitation. All without overheating you or weighing you down. They work like a jacket without the hassle of extra nylon which can cause unnecessary drag, friction and flap fatigue. They work like a long sleeve jersey but without all the sometimes hugely unnecessary thermal attention paid to your arms. They come in full zips. They come with pockets. They come in a range of materials and technologies. They're lightweight and effectively invisible. And some of them are packable which is basically like having an on/off switch for an already nearly perfect category of product.