It's amazing how much a simple collar can transform an outfit. It can make a sweatshirt go from lazy day grumble to well put together poise. It's simple and clean yet comfortable. If you're planning on layering with a sweatshirt make sure the collar and sweatshirt present a sense of constrast yet coordination with each other. For solid colored sweatshirts, a collar with a pattern of some sort ( stripes, floral, ect.) will add some pop and punch.