Everything you need, nothing you don't.
Big enough for you phone, your cards, your cash, and any bits and bobs that you really need. At the same time, it's not too big, to heavy or too intrusive to be carried all day. It's stylish enough to wear with just a t shirt in the summer, so good for holidays and travel. I wear mine under my coat in winter, it's great to have everything safely out of the way when I'm in central London. I've had a Citysafe for over 10 years, that's still going strong, so I've no worries about build quality, Pacsafe's last for years.