Does it fit Safety 1st slimride car seat or capsule?

Hi Sasa, the Britax Car Seat Travel Bag is designed to fit most Britax car seats and most other brands, except for Platinum PRO and Baby Capsules with a base. While it’s likely to fir the Safety 1st Slimride car seat, you may need to double-check the car seat dimensions to ensure it fits within the bag’s dimensions. You can find the bag’s dimensions here: (43.2 x 39.4 x 80 cm). Hope that helps