The city go car seat isofix base is the perfect partner for the baby jogger city go infant car seat so your baby can travel safely and securely in a rear facing position install using a cars isofix anchor points which will ensure your car seat is installed correctly every trip simply use the click in and out system and handy indicators to show the correct fitting the arm indicators that show green when the car seat base has been securely fitted and red when not the extendable support leg al