I have a two year old toddler and a 4 month old baby and was in a dilemma about whether to take a double buggy or two single buggys on holiday to Spain. I decided on two singles and purchased the Prince Lionheart buggy connectors to make it easier when my two year old wanted to walk with my one of us, it meant the other one could push the baby and the other buggy more easily and we wouldn't be struggling to get around narrow places with a double!
The buggy connectors were an absolute GODSEND, especially in the airports when my husband needed to push the trolley loaded with luggage. We connected the pushchairs and off we went and we were then able to seperate them again to sit in more congested areas and load them onto the plane. They were also handy when strolling along promenades and wider, open spaces.
You need two of the same pushchair or two very similar for the connectors to work and they are designed for light-weight, umbrella fold pushchairs in particular. They are white and a bit bulky and take a little getting used to, but overall an ingenious invention which I can't recommend highly enough!