The Nuna Aace will arrive in two main pieces - the tall backrest and the backless seating booster. To attach both pieces, you will need to align the hooks on the bottom of the backrest to the ones on the bottom booster. Then, slide them in, and you should hear an audible click, letting you know the assembly is successful. As for the installation, you can install the highback booster either by using lower latch connectors or the seat belt. The belt paths are color-coded, so you don't mess up achieving a proper installation. Nuna includes UAS connectors that are a perfect match for most vehicle seat models.