A Thule Sleek Car Seat Adapter is required to attach a car seat to the Thule Sleek Stroller.
Currently, adapters are available for certain car seat brands and models. The Maxi-Cosi adapter is compatible with select models from Maxi-Cosi, BeSafe, Cybex, and Nuna. The Chico adapter is compatible with several Chico car seat models.
Please check the compatibility lists for both accessories to ensure your car seat is compatible. These can be found in the Downloads section of each car seat adapter's product page.
No universal car seat adapter is currently available, though Thule is exploring designs for compatibility with other brands of car seats.