This is the pen I carry with me everyday — the Midori Traveller’s Company Brass Fountain Pen. Closed it’s 10cm in length so fits nicely in your pocket. I started using fountain pens last year as a way to improve my handwriting which had become so bad because of hardly ever writing anything apart from short printed notes. An extra side-effect of using this and other such pens is actually slowing down and thinking about what I’m writing. Happy to say my handwriting has improved a lot since forcing myself to put pen to paper.