Bowls for the inattentive

[Bowls that tilt when filled to their defined weight](http://www.royalvkb.com/sitemap/index.asp?page=1&submenu=1&prodid=%7B0B39FFDC-8878-415C-9D38-3C19274969E6%7D).

Clever. Wish I could work out how it works.