The Booklet 50 and Primo Viaggio 4-35 combine to create a streamlined, sophisticated and fully functional travel system. Together they open up the world for parents and baby to explore. The Primo Viaggio 4-35 car seat fits directly into the seat of the Booklet 50 using the G-Matic system, meaning no extra adapters are necessary when attaching the car seat to create this unique travel system. One purchase is all you need, take your family on new adventures with the Booklet 50 Travel System!