They're almost like fingerless gloves, but more comfortable and easier to manage.
You might be worried "but it's the fingers that are cold anyway, so fingerless gloves are not what I need." I thought that too, but trying them immediately proved me wrong and I never had an issue with cold fingers again. I'm fairly sure it's because warming your wrists/palms keep your blood from losing heat in those areas, so your fingers get much warmer circulation.
For something less than $10, it's probably the best purchase I've made for working in the winter