Hi Steph, Thank you for your enquiry. The main capsules that the Baby Jogger City Series Mini/ Elite/ Summit Car Seat Adapter is compatible with are the Maxi-Cosi Cabrio, Mico, Mico Nxt, Mico AP, Cybex Aton, Aton 2 and Aton Q, Nuna Pipa, Chicco KeyFit and Chicco KeyFit 30, Pego Perego Primo Viaggio SIP 30/30 and Primo Viaggio 4-35. Therefore this may not be suitable to fit the Unity Safe’n’Sound Capsule as it wont click into the attachment correctly. However, 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 experts can assist in helping check this for you and provide alternative options to assist you with you with your enquiry. We hope this has helped with your query.