Does this fit the safe n sound unity capsule as well as the larger car seats?

Hi Krystal, thank you for your enquiry, the Britax Seat Saver Waterproof Liner is only suitable for Britax Harnessed Car Seats and Strollers, it wouldn’t be suitable size for capsules. We hope this helps. ?For further information on this or any of our other products available, if you follow the link https://www.babyonthemove.co.nz/store-locations/ this will take you to our online store finder. Here you can find contact details for your nearest Baby On The Move Store where one of our team experts will be happy to assist you in your product search and help answer any further questions you may have. We hope this has helped with your query.