Amazon.com : BABYZEN YOYO Connect, White - Turn Your YOYO2 Stroller into a Double Stroller - Still Compact & Easy to Maneuver : Baby
YOYO Connect: The Ultimate Double Stroller – Mamas & Papas UK
Amazon.com : Twin Stroller Connector for Baby Universal Fits Umbrella Strollers Babyzen YOYO Yoya Etc.. Turns Two Single Strollers into a Double Stroller : Baby