Nice thin straps, and if they do show from under a wide neckline, they would look like camisole straps.  Low enough cut for most tops.  No uniboob; nice, natural look.  Yes, everyone will know if you are cold when you wear this under a t-shirt.  I am a 34A, and the Small fits me well.  (I always wash bras in cold water and hang dry, so that they last longer.)