Yes, it will fit any of the already existing Bugaboo Cameleon, Donkey, Buffalo and Bee seat units. They are able to sit forward or rearward facing on the chassis and is an ideal investment if you are wanting to jog with your little ones in a pram.
It can also be bought as a complete jogging pram system but the option to buy the chassis only if you already have a Bugaboo pram is a really fab idea and gives you the flexibility to choose between your existing Bugaboo chassis or the Runner option.
It's large 16 inch back wheels and 14 inch front wheel along with it's sleek frame makes it just as sturdy as a Bugaboo pram should be with the excellent option of being able to use it to jog with, which isn't recommended with other prams. It also has a handbrake and footbrake which is fab for extra safety and reassurance if you are either running or just using it as a walking pram and as always has a generous sized underseat basket.